Showing posts with label Volkswagen. Show all posts
Showing posts with label Volkswagen. Show all posts

Wednesday, November 9, 2022

On-Board Diagnostics

ON-BOARD DIAGNOSTICS 

A few days ago I was driving behind a string of cars through Liesbeek Parkway when I was startled by several drivers repeatedly  hooting at an Audi A4 driving in front of them to get out of the way or change lane. The Audi A4 that was holding up the traffic had a Guateng registration plate and  my first impression was that its occupants got lost at the spaghetti junction fly-over, not knowing which off ramp to take.

However when these impatient hooting drivers finally overtook the Audi A4 and I got to drive behind it;  I then realized that the Audi A4 was in fact in Limp Mode. Its driver was attempting to get to the shoulder of the road from the centre lane and the traffic just wasn't easing up.

In my opinion, these impatient driver just weren't aware that when a vehicle goes into Limp Mode it cannot go any faster than it's already going even though its driver was flooring the accelerator pedal. And I may add that ignorance about Limp Mode is no excuse, because its been around since 1996.


Vehicle Delivery Services Salvaged Limp Mode car


DRIVER COURTESY

Driver courtesy is very important to bolster safe driving conditions for everyone but an education regarding Limp Mode would be considered far more important. When a car suddenly reduces speed after driving at normal speed, it could be one of several reasons; among which could be steering vibration due to a puncture. Or the vehicle ran out of fuel. Or the engine may have switched off due to a dead battery caused by either alternator issues or snapped fan belt. 

Or the engine may be overheating, or the driver heard a disturbing noise coming from the engine. Or it could be an electrical fault like a faulty fuel pump or an ignition system failure like a defective engine or transmission control unit. Or the driver could have fell ill behind the wheel, to mention but a few of the myriad of reasons why a vehicle could stall or it may have entered in Limp Mode. 

AUTOMATIC TRANSMISSIONS

The engines of cars with automatic transmissions can sometimes switch off mid travel for some obscure reason. The only option the driver has, is to pull off the road, bring the car to a halt, place it in park or neutral to restart the engine. I know of someone who shifted his automatic transmission into neutral when the engine cut out mid travel, restarted the car and shifted it back into drive. This caused his car to almost come to a stand-still instantly causing the wheels to screech as the engines inhibited the transmission.  This type of action can and probably will damage the transmission subject to the gearing system inside and should never be done. Unfortunately no On-board diagnostics makes provision to prevent this.

When an engine cuts out at say 100kph both the power steering and vacuum boosted brakes stops working, thereby making steering difficult and the braking inefficient. It is therefore best to pull off onto  the shoulder of the road and check what the problem is an remedy it before continuing on your journey.

ON-BOARD DIAGNOSTICS

On-Board Diagnostics does a pretty decent job of protecting the engine and transmission against damage by limiting  acceleration, keeping the engine revs to a maximum of 2000 (RPM) and speed to about 45kph - aka Limp ModeWhen Limp Mode is enabled, it may lock an automatic transmission  in low gear and even disable both heating and air conditioning. Yet keeping the engine running so that it can be driven to a repair shop.

However, as clever as an ECU is,  it doesn't do anything to alert the driver of the car that follows close behind. Considering tail lights, brake light, reverse lights and  indicators represents a language used by vehicle drivers for those  following behind, to indicate their driving intentions. This light language that's been around for the better part of the automotive industry's existence yet it still haven't come-up with an appropriate and safe warning sign/method for Limp Mode. 

LIMP MODE INDICATOR

To remedy this, car manufacturers could include flashing hazard lights or perhaps fit an LED Display with a scrolling message along the the rear window as an alert to tell the driver following behind that the car in front of it has gone into Limp Mode. Alternatively, electronics savvy car owners can fit their own aftermarket hack by identifying the switching output of the appropriate automotive  High Side Switch (HSS) responsible for protection and diagnostics inside the ECU when Limp Mode is enabled.

Automotive industry High-Side Switches /Drivers - Integrated Circuit 

This may not be as easy as it may seem or sounds because of the myriad of automotive chip manufactures, each pushing their our integrated circuits (ICs) running custom/propriety software, among which are Infineon Technologies AG,   Robert Bosch, Qualcomm, Renesas Electronics Corporation (Intersil), NXP Semiconductors,  STMicroelectronics, Texas Instruments, Intel and Microchip Technology Inc, etc.

However, most of these manufacturers produce Power Switches and incorporate Open Load Detection in their design so that they can perform open-circuit diagnosis on loads, such wiper motors, fans, head lamps, fuel pump, mirrors, actuators in general and LED lights while  the load is enabled or disabled. Open load diagnosis is probably the most important function of the software driven High-Side Switch (HSS) and Low-Side Switch when wired in a specific configuration which allows for currents from 5mA to more than 10A to be accurately detected.   

As such able to generate a hardware signal (Limp Mode signal) that can directly control the hardware without the participation of the microprocessor in the ECU. This output can be used to as either a digital High of Low (using CMOS inverter) to drive a LED display that flashes LIMP MODE..... LIMP MODE..... LIMP MODE.....



Thursday, November 3, 2022

Overactive Check Engine Light

AUTOMOTIVE RELIABILITY  

All automotive manufacturers have reliability issues with some or certain of their vehicles and Volkswagen is no exception even though it is one of the largest car manufacturer in the world. Globally the masses buy cars in general based on its looks (aesthetics), price, performance and reliability but not necessarily in that order.

In my opinion, reliability play a major role in decision making and should always be considered first. Hence, the question that begs to be asked is, "What's the use of owning a smart looking car with better than average performance that you acquired at a very attractive price but is as unreliable as a career politician". 

Understandably car manufacturers at times produce lemons (The Monday Car) or unknowingly fit a substandard part to some of the vehicles which only becomes apparent when it starts to fail in the field, necessitating a recalls. However, often times these troublesome parts slip through the cracks and fail infrequent enough and disparate enough as not to alert car owners to this pending problem and that is replaceable under recall. 


PCV valves

As a consequence car owners foot the repair bill for something that may never have been necessary to fix or replace if the manufacturer did their due diligence by adequately testing these parts before use. Any and all parts not tress tested or burn-in tested invariably fails and these failing parts then becomes known as Common Problems that plague the car owners.

Case in point, the Volkswagen Jetta 2006 - 2019 appears to have the most issues — aka Common Problems — necessitating seven (7)  major recalls due to some 295 complaints by owners to the National Highway Traffic Safety Administration (NHTSA). When these statistics are compare to the more reliable models, like the Volkswagen Golf GTI and the Tiguan which had absolutely no recalls and a very small number of complaints registered with the NHTSA, one notices the reliability factor.

MISLEADING DATA


This reminds me of how computer hardrives manufactures like Seagate, Western-Digital and Hewlett-Packard etc label hardrives by rating them at 1 Million hours 
 — MTBF (mean time before failure). One would be misled to believe when manufacturers as a whole guarantees the item/part in question for 1 million hours of operation before failure,. Whereas the said item has not even been in existence or production for this length of time, let alone tested for failure for this duration. One (1) million hours roughly equates to 114 years, so one can see how misleading that rating really is.

WHAT MTBF REALLY MEANS


Having said all that, I feel that MTBF is a really bad measure for determining the probable life span of any item, be it a hardrive, a light bulb, a printer, a TV, a car part or an entire car. However, what MTBF really means, is that if the manufacturer built 1 million units and started running burn-in test on all of them at the same time, one item is expected to fail per hour.  The same hold true for producing 5000 units, implying 1 unit will fail every 5000 hours. This is especially true for electronic components, its failure varying between the stringent implementation or slack specification and tolerances they are manufactured under. 

The German tradition and culture of manufacture in general gives rise to vehicles one can rely on with proven reliability and durability based on robust design, assembly, pride and attention to detail. This is noticeable on cars built and assembled in  Wolfsburg, Lower Saxony, Germany when compared to German designed cars manufactured/assembled elsewhere among which are South Africa, Mexico, Brazil, Asia etc. 

If your Volkwagen's VIN number starts with SN, ST or W you have a car that may outlast you whereas any other "world manufacturer identifier" prefix will virtually guarantee you a life of replacing parts. Purely because they are assembled from parts originating from ancillary OEM parts manufacturers and Chinese auto parts manufacturers instead of genuine VW parts originating from Germany.

Common Problems on Volkswagen vehicles mainly stems from these sub-standard rogue parts and several of them may be responsible for your Overactive Check Engine Light, from your leaking coolant, to excessive oil use and smoking, to engine overheating, to mention but a few.

EXCESSIVE SMOKING


Hard plastic has become the preferred product from which to manufacture modern day car spare parts —  in place of diecast aluminum machined to perfection —  and is used in abundance in most cars to reduce manufacturing costs, the overall weight of the vehicle that consequently improve its millage. 

However these plastic parts do become brittle over time thus prone to failure due to the engine heat. For example a blocked plastic PCV (Positive Crankcase Ventilation) valve  responsible for extracting the blow-by gases from the crankcase —  may be the cause of rough idling, poor acceleration and an increase in oil consumption and as a consequence excessive exhaust smoke. When detected by to O2 sensor will cause the Check Engine Light (CEL) to trigger.

OVER HEATING


Plastic thermostat assemblies commonly leak prematurely when they become contaminated by engine oil from a leaking PCV system. This may lead to that stubborn coolant leak that you cannot find  is more-likely-than-not caused by plastic pipe couplings, plastic hoses connectors, or perhaps the plastic radiator tanks located behind the AC condenser  that developed a minute crack, all able to cause overheating.



Wednesday, August 24, 2022

VW POLO CANBUS

VW POLO CANBUS

If you own a Volkswagen Polo, you more likely that not already know that a Controller Area Network (CAN) bus is an automotive wire network loosely referred to as a bus. The word "bus" comes from the electrical power distribution sector where bus-bars were considered a metalic strip made of copper, brass or even aluminium that served as a source of electric power to the load. 

CAN BUS

However CAN Bus is more akin to Ethernet than a bus-bar. Ethernet is a computer networking technology using Unshielded Twisted Pair cable (UTP) either CAT5 or CAT6 which is now commonly used in local area networks capable of sending  IPv4 / IPV6 packet across its networks at speeds ranging from as slow as 10Mb/s to as fast as 1000 Gb/s, hardware dependent of course. 


CAN BUS Network Wires
Twister pair electrical wires with various colour tracers.


Likewise CAN is a network technology commonly used in automotive networks capable of sending CAN-frames across its network at various speeds, again application dependent. It is essentially a  very reliable multi-master arbitration free serial bus, connecting numerous Electronic Control Units (ECUs) aka nodes together.

CAN BUS vs ETHERNET

The big difference between the two, is that Ethernet is an 8-wire bus comprising of 4 unshielded twisted pairs of wire, each with a specific colour coding, whereas CAN has only a single unshielded twisted pair of wires also with a specific colour coding. The CAT5 protocol insists on 2 twists per centimeter and CAT6 with more twists per centimeter whereas the CAN protocol insists on a 1 turn per centimeter. The lay of these wires are very specific and necessary to reduce or cancel interfering signals picked up from the environment by them, which is more commonly referred to as "crosstalk".

CAN BUS HIGH & LOW

Bearing in mind CAN comes in two varieties used for different functions, viz CAN-High (CAN-H) and CAN-Low (CAN-L).  CAN-H is used for the Powertrain, the Convenience and Infotainment buses. 

Whereas CAN-L is used for the rest of the bus wiring.  Both CAN-High and CAN-Low uses different colour wires for different makes of vehicle. For example:-

Manufacturer        CAN High        CAN Low
Mercedes                  Brown/red         Brown
Volvo                        White                Green
Vauxhall                   Green                White 
BMW 1 & 3             Green/orange     Green 
BMW 5 & 6             Black                 Yellow 
Porsche                     Yellow              Black


The big difference between the three buses for VW,SEAT, Skoda and Audi is that:-

1) The Powertrain bus wires interconnected to all the powertrain modules / nodes are coded Orange & Black CAN-H 

2) The Convenience bus wires interconnected to all the convenience modules / nodes are coded Orange & Green CAN-H 

3) The Infotainment bus wires  interconnected  to the infotainment modules / nodes are coded Orange & Violet /Purple CAN-H 

4) CAN-L bus wires to all the interconnected convenience modules / nodes are coded Orange & Brown. (Electronics colour code 31)

REPAIRING WIRES

CAN wires are typically multi-strand 0.35mm to 0.5mm square with 120 ohm termination impedance, capable of transmitting information using two complementary signals which makes them even less prone to crosstalk. But thin wires are prone to break and if and when they do, it is recommended  that when repairing these CAN Bus wires, that both wires must always remain the same length and of equal thickness. 

Implying CAN BUS is extremely unforgiving. So, when wire 1 of the pair is broken, wire 2 should also be cut and the piece of wire added in-between must be exactly the same length; and that the lay length of 1 turn per centimeter must be observed. 

ELECTRICAL INTERFERENCE

Failure to do so, may created a discrepancy in the wire length of the one wire in the twisted pair as well as in their differential voltages, hence result in network errors — ground noise, electrical interference, hum, buzz,  spark plug spikes — cannot and will not be appropriately cancelled. 

Whenever repairs are made to any CAN Bus wiring, it is highly recommended that all CAN Bus wire repairs are covered and highlighted with yellow insulation tape to signify to anyone doing successive work, that a previous repair was carried out. 

That EPC light

That EPC light.

The most likely reason you're reading this blog post, is because you encountered an EPC fault with your Volkswagen vehicle. I bet you wondered what that yellow/orange light was when it lit-up or perhaps startled when you car went into "limp mode". Whether you're driving a VW Polo or VW Jetta, VW Golf,  VW Caddy, VW Passat, T-Cross, Sharan, Touareg, Transporter, or any other Volkswagen or even a German Audi, or a Czech Skoda or a Spanish VW SEAT, you've come to the right place because they all have an  Electronic Power Control circuit. 



In fact all "modern day" vehicles have EPC circuit, which loudly says that the automotive industry have finally reached some consensus on standardization. But let me tell you what the EPC light actually is. It's just a signal light informing you that there is an error in your vehicles torque circuit. That's the short answer, however, I can tell by the look on your face that it wasn't a  satisfactory answer, so let me give you the long version.

The EPC light is part of the Electronic Power Control Circuit which is just one of the components of OBD-II which was mandated by a certain regulatory bodies with regulatory intent. Their initial intention was to limit carbon emissions / exhaust fumes from cars on the street of America. 

The California Air Resources Board (CARB) and the Environmental Protection Agency (EPA) together with the Society of Automotive Engineers (SAE) and the International Organization for Standardization (ISO) collectively originated the On-Board Diagnostic (OBD) System because of high levels of smog produced by automobiles throughout the USA.  

Their initial On-Board Diagnostic System was subsequently superseded by the all new and improved verion OBD-II, hence all cars manufactured post 1996 has an Electronic Power Control Circuit and by extension an EPC light. The European on-board diagnostics (EOBD) regulations are the European equivalent of the American OBD-II. 

On-Board Diagnostic (OBD-II) is an automotive mechatronic, micro processor / micro controller based computer system with programmed presets that continuously monitors inputs from numerous sensors fitted through the car. 

It then computes/compares/ compensates these inputs against stored data and drives various actuators to perform certain tasks. In a nutshell OBD-II is an input/output (I/O) information processing system much like the PC / laptop / or even your smart phone. By example, a keyboard, a mouse, a joystick, a scanner and a microphone are common computer input devices whereas a HD monitor, a printer, speakers and headphones are common computer output devices. 

Here the computer/laptop makes calculations based on its internal operating system and software to do something intelligible for humans. However in the case of OBD-II, its CPU (Central Processing Unit) is called an ECU (Electronic Control Unit) and among its input sensors are the Accelerator Position Sensor, Mass Air Flow sensor (MAF), Lambda O2 Sensor, Knock sensor, Oli level sensor, Coolant Temperature Sensor, the Camshaft Position Sensor, the Crank Position Sensor, the Wheel Speed  Sensor etc, to mention but a few.

Among its output actuators and solenoids are the drive-by-wire electronic throttle actuator, the fuel injectors, the EPC light, Malfunction Indicator Light (MIL), the Immobilizer, the Airbags and the Power Steering Pump, etc, again to mention but a few,

This ECU is sometimes referred to as an Engine Control Unit especially when intending to make reference to the TCU (Transmission Control Unit). The ECU is sometimes even called ECM (Engine Control Module) when making reference to other electronic control modules like the ABS module, the Instruments module, the Central Electronics Module, the CAN gateway module, the Radio Module, etc, again to mention but a few 

However, the ECU and the TCU are collectively referred to as Powertrain Control Module (PCM). The ECM essentially controls the efficiency of the engine performance by using a Crankshaft Position Sensor to determine the position of the cams in order to activate the injection of fuel into the cylinders and the timing of the ignition spark to ignite it at precisely the correct moment in petrol engines. 

Likewise the ECM in Diesel engines, plays a huge role in the success of the turbodiesel models. But in order for this to happen, an electronic throttle control had to be introduced, replacing the  cable from the pedal to the carburetor system which was prone to idle speed deviation between a hot and cold engine that became more and more prevalent as the components wore out. 

In so doing, the ECM can adjust the electronic throttle angle during acceleration to achieve the right quantitative relationship ratio between the actual airflow through the engine and the injected fuel thus maintaining Stoichiometry. Controlling the throttle airflow on the fly, markedly improves overall torque and driveability which is known as torque-mapping, an advantage that is only possible with drive-by-wire. 

So, the Electronic Power Control Circuit consists of the ECM, the Accelerator Position Sensor, the Throttle Position Sensors, the Throttle Actuator, the MAF / Air Filter, the Fuel Injectors, the High Pressure Fuel Pump, Fuel Temperature Sensor, Fuel Rail Pressure Sensor and Pressure Relief Valve. 

The single accelerator position sensor is made up of two individual potentiometers each acting independently of the other but collectively operate with opposite polarity voltages supplied by the ECM, as a safety back-up for one another. 

Thus, if either potentiometer fails, the ECM will activate limp mode. This is a safety measure that prevents the system from acting as if it had an accelerator cable that got stuck in the runaway position and the makings of a potential accident. The cruise control also has influence on the throttle body and requires the brake pedal to be depressed to cancel the cruise control. 

The ECU normally takes this cancellation signal from the brake light MOSFET low-side driver in the ECU. So either the brake pedal switch and the a brake light bulb can cause an EPC error along with the aforementioned fuel supply components. It's best to have a diagnostic tester to check for DTC errors via the DLC connector. It would at the very least steer you in the right direction to fix your EPC problem effectively.

Annoying VW EPC light

VW EPC expounded

As I've explained in an earlier blog, the amber Electronic Power Control warning light on your car's instrument cluster, is just an indicator light; drawing your attention to either (1)  an Auto-Correct EPC Problem, (2) a Pending EPC Problem, (3) an Existing EPC Problem or  (4) a Current EPC Problem. 

An Auto-Correcting  EPC problem occurs when the EPC light goes on without noticeable difference in engine performance and goes off during subsequent drive cycles which may be within a day or two or longer.

A Pending EPC Problem could be something as simple as a spark plug misfiring intermittently and appears in the scan list but after a while becomes an Auto-Correcting EPC problem alternatively if the plug continues to misfire it becomes and Exising EPC problem.

An Existing EPC Problem could be something like the MAF sensor or a accelerator pedal sensor that needs cleaning or replacement and a Current EPC Problem normally results in limp mode.



EPC light is bright YELLOW/AMBER and acts as a indicator, it is not as a warning light. 
Warning light are always RED.

EPC light is bright YELLOW/AMBER and acts as a indicator light, an advisory light; it is not as a warning light.  Warning light are always RED. Since the ECU "learns your driving style" over time, it records your optimize drive cycles to non-volatile memory along with atmospheric pressure, min & max rpm and the average fuel use data, etc, then creates an adaptive pattern or map based on these parameters. 

When this map is compared to sudden spirited driving, it may trigger the EPC light but will auto-correct (reset) itself after a few driving cycles within a day or two. Sometimes the EPC light may be accompanied by the Check Engine Light (CEL).

A Pending Problem can cause the EPC light to come and not switch off on its own. Pending implies that the problem will only get worse if left unattended to. A diagnostic scanner is needed to view the DTC error, hence its really worthwhile investing in one. 

For example, assume that cylinder number 3 randomly misfired a few times as the pending problem. The scan freeze frame data will show something like this.

000771 - Cylinder 3
               P0303 - 000 - Misfire Detected - Intermittent
             Freeze Frame:
                    Fault Status: 00100000
                    Fault Priority: 2
                    Fault Frequency: 7
                    Reset counter: 255
                    Mileage: 38187 km
                    Time Indication: 0
                    Date: 2021.11.05
                    Time: 21:09:58


             Freeze Frame:
                    RPM: 758 /min
                    Load: 13.1 %
                    Speed: 0.0 km/h
                    Temperature: 51.0°C
                    Temperature: 33.0°C
                    Absolute Pres.: 830.0 mbar
                    Voltage: 12.435 V


What this means is that cylinder misfired 7 time, and that the most recent misfire occurred at the displayed time and date highlighted in red and has a fault priority of 2.  Fault priority of 4 or lower needs to be attended to immediately since it affects the driveability of the car. Don't ignore the VW EPC light.  

Fault priority of 5 and above doesn't require immediate attention but must be attended to sooner rather than later. The freeze frame date shows that the car was idling and 758 rpm with the speed at 0 kph and that the engine hasn't reach its optimum operating temperature as yet. In a nutshell, freeze frame captures the engine operating conditions at the time when the EPC error occurred.

An Existing EPC Problem could  mean either the throttle pedal, throttle body, or brake control unit or any other circuit related to the torque circuit, like the  cruise control unit or the traction control unit is misbehaving.  However the EPC light can also indicated an unrelated problem like a loose fuel cap. With the EPC light on, and a pungent fuel smell inside the cockpit would point you to fuel cap.  

Since the fuel is under pressure, the fuel pump, fuel regulator or fuel rail pressure sensor may also be suspect, each should be excluded through a process of elimination. Remember the Electronic Power Control system is integrated with several other systems on you vehicle, like the steering control unit and the ECU, hence it's not always easy to diagnose.

Its permissible to  drive your VW for a short distances and for a short period of time after the EPC light has triggered, that's to say if driveability hasn't been impaired but its best to either fix it yourself or take it to  VW service center. An  EPC dashboard light can be caused by any of the following, but in no particular order. Sometimes both the EPC light and CEL (check engine light) would turn on.

1) Brake Light Switch failure
2) Mass Air Flow Sensor failure 
3) Engine Speed Sensor failure 
4) Throttle System Potentiometer Failure
5) Cruise Control failure
6) Accelerator Pedal Potentiometer failure
7) Repeated cylinder misfires
8) Loose fuel cap
9) Blown / Faulty  brake light

Any of these can and may cause your vehicle to go into “limp mode” which can be described as a Current EPC Problem. When limp mode strikes, the Engine Control Unit will limits the functions of the torque circuit and transmission thus prevent your VW's engine from  revving higher than 2000 rpm and limit its speed to 30-45 kpm. 

Some mechanics would reset the EPC light by cleasing the DTC list without fixing the actual problem but this is not recommended. When the  Diagnostic trouble codes (DTC) are cleared,  "your driving style" map is also deleted, meaning that the ECU would have to relearn  "your driving style"  from scratch and your VW's performance may seem a bit off.  That's to say, until your racked up sufficient drive cycles (data) with which the ECU can do an analysis in real time. 

Thursday, February 24, 2022

The Most Common Car Problems

The Most Common Car Problems

There was a time when car owners could easily service their own cars. Simply replacing points, plugs and condensors,  draining its oil and replacing its oil and oil filter normally put the car back on the road again. Those were the days when the most common roadside problem was a puncture or a snapped fan belt. Punctures were easily fixed with a replacement tyre from the trunk. All that was needed was some elbow grease applied to the jack, wheel brace and wheel nuts and you were on the road again. But today rollbacks are are integral part of motoring. Hundreds of cars are loaded up everyday on the road side.


VW Polo on a roll back going to workshop


The main cause of punctures was attributed to poor road surfaces, random metal objects and broken glass and to a lesser degree older tyre technology. Even though punctures were predominant, they were by no means exclusive to roadside breakdown because clutch plates and gearbox problems were also plentiful, as was running out of fuel.


Volkswagen Polo on a roll back

With the advent of newer cars, the race for the most fuel efficient and least expensive car was on. When fuel and air stoichiometrics were at its peak, car manufactures started producing cars with a 'Space Saver Biscuit Spare Wheel' which took several kilograms of weight out of the trunk, This made the car a tad lighter, slightly more fuel efficient and ever so slightly, cheaper to produce.

Today, almost a third of all new cars don't even have a spare wheel; instead they may be equipped with a can of self inflating puncture-repairing foam, or an electrical air compressor with some sealant kit to temporarily fix a flat tyre. Both options are evidently cheaper than a Space Saver Biscuit Spare Wheel and lighter.



However, believe-it-or-not, the more expensive cars today, are sold without  a spare wheel, instead they are fitted with “run-flats”. In a nut-shell, run flats are special pneumatic tyres, designed to resist the effects of deflation when punctured, yet enables the car to  be driven at reduced speeds of under 90 km/h for a distance of up to 80 km. The speed and distance of course to the nearest tyre repair shop, is subject to the type and quality of the run-flats.  So, once again the manufacturer saves the cost of supplying a spare wheel.

Car on rollback

Be that as it may, snapped fan belts  often causing the engine to overheat, sometimes resulted in a  blown  cylinder head gasket. Subsequently, the modern day electric radiator fan has totally supperceeded the belt driven fan and as a result, burst radiator hoses, corroded, leaking water pumps and welch plugs have  became the primary cause  of blown cylinder head gaskets. The other bugbear is oil leaks that weren't timeously attended to, currently trending as the most common cause of seized engines. 

With the abundance of electronics fitted into cars, the alternator  and its voltage regulator have  became a lot more more troublesome than ever before. Obviously due to the additional electrical load.  Alternator  problems are closely followed by starter issues when either its brushes or its  bendix reaches its end of life.   



Both types of problems have resulted in batteries being replaced prematurely and sometimes unnecessarily. Brakes and Turbos also give their fair share of problems, but none of these problems comes close to the new type of roadside breakdowns caused by the OBD-II system.

The most common cause of  breakdowns today, is the Electronic Power Control (EPC) light; not that the light is the cause of the problem. The Electronic Power Control (EPC) light is only an advisory light, drawing your attention to a possible malfunction or  pending problem or  already existing problems.



When the Electronic Power Control (EPC) light comes on, without the ESP or Check  engine light, the car is normally still driveable, even if it goes into limp mode. But when accompanied by the ESP and or CEL (check engine light) the car may refuse to start as its inhibited by the Electronic Computer Unit (ECU). 

When this happens, the only solution is to secure a rollback to fetch the car and take it either to your service agent / mechanic or your home, so that you can tend to the problem yourself. 

There is no way you'd be able to effect repairs to your car yourself without a OBD II scanner   that would direct you to, or confine your repair to a certain area of the engine. 

ODB-II problems not limited to VW.

Below are a few sample yet partial ODB II diagnostic scans  for Electronic Power Control (EPC) problems. 

This for a 7N0 - VW Passat.
Address 01: Engine (CDL)       Labels: 06F-907-115-CDL.clb
   Part No SW: 1P0 907 115 AB    HW: 8P0 907 115 B
   Component: 2.0l R4/4V TFSI     0020  
   Revision: 5BH20---    Serial number: 0000              
   Coding: 0303004C18070160

1 Fault Found:
008487 - Accelerator Position Sensor 2 (G185) 

               P2127 - 002 - Signal too Low


Electronic Power Control (EPC) problem  for a 1J - VW Golf.

Address 01: Engine Labels: 06A-906-032-AWP.lbl
Part No: 06A 906 032 RN
Component: 1.8L R4/5VT G 0001 
Coding: 07510

18047 - Accelerator Position Sensor 1/2 (G79/G185) 
            P1639 - 35-00 - Implausible Signal
18042 - Accelerator Position Sensor 2 (G185) 

            P1634 - 35-10 - Signal too High - Intermittent



Electronic Power Control (EPC) problem  for a 7L - VW Touareg 

Address 02: Auto Trans        Labels: 09D-927-750.lbl
   Part No: 09D 927 750 AN
   Component: AL 750 6A           0546  
   Coding: 0004153


1 Fault Found:
00777 - Accelerator Position Sensor (G79) 

            004 - No Signal/Communication - MIL ON


NB! The Automatic Transmission module and not the Engine Module detected this accelerator sensor problem.

 


Electronic Power Control (EPC) problem 1H - VW Golf/Vento III
Address 02: Auto Trans       Labels: 01M-927-733.LBL
   Controller: 01M 927 733 CT
   Component: AG4 Getriebe 01M    3363
   Coding: 00000
    

1 Fault Found:
00518 - Throttle Position Sensor (G69)

            16-10 - Signal Outside Specifications - Intermittent


NB! The Automatic Transmission module and not the Engine Module detected this accelerator sensor problem. Here the Throttle position sensor instead of the Accelerator sender is the cause of the problem.


Electronic Power Control (EPC) problem  for a 9M - VW Jetta IV.
Address 01: Engine Labels: 06A-906-032-AWP.lbl
Part No: 06A 906 032 RN
Component: 1.8L R4/5VT G 0001 
Coding: 07510

1 Fault Found:
18047 - Accelerator Position Sensor 1/2 (G79/G185

P1639 - 35-00 - Implausible Signal 



Electronic Power Control (EPC) problem  for a 8E - Audi A4.
Address 01: Engine Labels: 06C-909-559-ASN.lbl
Part No SW: 8E0 909 559 D HW: 8E0 909 059 
Component: JHM V3/9X G 0003 
Coding: 0016751

2 Faults Found:
18047 - Accelerator Position Sensor 1/2 (G79/G185) 
P1639 - 008 - Implausible Signal - Intermittent
18047 - Accelerator Position Sensor 1/2 (G79/G185) 

P1639 - 008 - Implausible Signal - Intermittent - MIL ON



Electronic Power Control (EPC)  for a 8P - Audi A3.
Address 01: Engine Labels: 06A-906-033-BGU.lbl
Part No: 06A 906 033 DS
Component: SIMOS71 1.6l 2V 5559 
Revision: --H03--- Serial number: AUX00000
Coding: 0000071

4 Faults Found:
18047 - Accelerator Position Sensor 1/2 (G79/G185)

P1639 - 008 - Implausible Signal - Intermittent



Electronic Power Control (EPC) problem  for a 9M - VW Jetta IV


Address 01: Engine Labels: 06A-906-032-AWP.lbl
Part No: 06A 906 032 LP
Component: 1.8L R4/5VT G 0005 
Coding: 07500

18042 - Accelerator Position Sensor 2 (G185) 
P1634 - 35-00 - Signal too High
18039 - Accelerator Position Sensor (G79) 

P1631 - 35-00 - Signal too High



 Electronic Power Control (EPC) problem  for a 1C - VW New Beetle

Address 02: Auto Trans Labels: 01M-927-733.lbl
Part No: 01M 927 733 EN
Component: AG4 Getriebe 01M 4108
Coding: 00000

1 Fault Found:
00518 - Throttle Position Sensor (G69)

16-10 - Signal Outside Specifications - Intermittent

NB! Once again the Automatic Transmission module  detected this Throttle position sensor instead of the Engine Module detecting the Accelerator sender to be the cause of the problem.

___________________________________

As can be seen from the data above,  there are essentially 3 types of  DTC errors responsible for triggering the EPC light, though not exclusively. P codes  P1630 and P2122;  P1631 and P2123;  P1632 and P1861 are essentially the same and applies to sender 1. 

As can be seen below.
P1633 and  P2127;  P1634 and P2128; P1639 and P2138 are essentially the same but applies to sender 2. There are also several other DTC errors that can and trigger the EPC and or along with the ESP, and or with the CEL.

Accelerator Pedal Sensor 1

P1630 - Accelerator Pedal Pos. Sensor 1 (G79), Signal too Low
P1631 - Accelerator Pedal Pos. Sensor 1 (G79), Signal too High
P1632 - Accelerator Pedal Pos. Sensor 1 (G79), Power Supply Malfunction

P2122 - Accelerator Pos. Sensor 1 (G79), Signal too Low
P2123 - Accelerator Pos. Sensor 1 (G79), Signal too High
P1861 - Accelerator Pos. Sensor 1 (G79), Error Message from ECM

Accelerator Pedal Sensor  2

P1633 - Accelerator Pedal Pos. Sensor 2 (G185), Signal too Low
P1634 - Accelerator Pedal Pos. Sensor 2 (G185), Signal too High
P1639 - Accelerator Pedal Pos. Sensor 1/2 (G79) / (G185), Implausible Signal

P2127 - Accelerator Pos. Sensor 2 (G185), Signal too Low
P2128 - Accelerator Pos. Sensor 2 (G185), Signal too High
P2138 - Accelerator Pos. Sensor 1/2 (G79) + (G185), Implausible Signal

Throttle Position Sensor

16505/P0121/000289 - TPS (G69): Implausible Signal
16506/P0122/000290 - TPS (G69): Signal too Low
16507/P0123/000291 - TPS (G69): Signal too High

Throttle Angle Sender 1

17950/P1542/005442 = Angle Sensor 1 for Throttle Actuator (G187): Implausible Signal
17951/P1543/005443 = Angle Sensor 1 for Throttle Actuator (G187): Signal too Small
17952/P1544/005444 = Angle Sensor 1 for Throttle Actuator (G187): Signal too High 
 

Throttle Angle Sender 2

16605/P0221/000545 - Angle Sensor 2 for Throttle (G188): Signal   Implausible 
16606/P0222/000546 - Angle Sensor 2 for Throttle (G188): Signal Too Low
16607/P0223/000547 - Angle Sensor 2 for Throttle (G188): Signal Too High


Depending on the model of your vehicle, its Throttle position sensor (TPS) lowest output voltage should be around .17 Volt and when the Electronic Control Unit (ECU) detects that it has dropped below that, then it will trigger either a P0122 or P0222 code.  High signals are not common but they do occur. 

 

As can be seen from the above data the error signal is either too low or to high or intermittent/implausable. Bearing in mind that a constant 5 volts is supplied by the ECU via a High-side or Low-side driver to the each of these potentiometers (senders). Loss of the voltage or even intermittently loss will trigger the EPC light and enter into "limp mode".

By implication  the monitored output is in 1 of 3 states, viz, low, high, or intermittent. In order to determine these states, the ECU needs a reference to compare these signals against. Each sender therefore act as a reference for another and any discrepancy between the two can result in an EPC error and subsequent limp mode. 

Replacing the Accelerator Pedal sensor (potentiometer)  unit normally fixes the EPC problem, but limp mode can also be caused by the throttle butterfly potentiometer.  And like I mentioned before, an OBD-II diagnostic tester would make this repair a lot easier and a lot faster.


NB! When your car goes into "limp mode", you may have  a lit   "Engine Management Light" (EPC icon) and or a "Electronic Stability Light" (skidding car icon) and or a "Engine Control Lamp" (engine icon) or any other combination thereof.  


Even Earthworks machinery are fitted with OBD-II so that exhaust emissions can be controlled but when there is a problem in the OBD-II system, invariable these machines would have to go on a roll back and taken for repair.

 

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Tuesday, January 4, 2022

Common OBD-II problems

Common OBD-II Problems

OBD-II has now been in our faces for a "Quarter Century" and even though it works fairly efficiently to control the hydro-carbon emissions in post '96 vehicles to some degree, it isn't as effective as some people would've liked, in terms of its diagnostic accuracy or as transparent and simplistic in its use to aid the layman.  On the flip side, many people with several mechanics among them completely abhors OBD-II and sees it more as a hindrance that a help and even add that they prefer cars not to have OBD-II. Since its inception, OBD-II has stymied mechanics globally, especially when the OBD-II system shuts down the engine and turns on the  EPC Light or Check Engine Light. And today, some 25 years later most car owners and mechanics still suffer fits effects yet endure the wrath of OBD-II. However, regardless of what we as lay people say, OBD-II is here to stay and we cannot wish it or will it away. 

Genuine Volkswagen Audi - Harness - 1KD971658
Genuine Volkswagen / Audi Harness Mfg Part #: 1KD971658

Personally I think OBD-II is a great in all aspects and incarnations however it has its drawbacks. OBD-II  does place car owners at a huge disadvantage and at risk when it fails. Purely because the problems are not evident but rather masked by the mysteries of electronics technology. This very often leaves them stranded and in a dangerous situations when stuck in the middle of nowhere. With the result that even the DIY car owners cannot do any repair work themselves, but have to resort to phoning  a salvage company to come  load their vehicle onto  a rollback.  Unless of course they have previously invested in a OBD-II scanner  and is able to check for DTC error codes.  But as the saying goes, "most people only lock the stable after the horse has bolted". 

Another drawback of OBD-II is that since car owners in general do not own diagnostic scanners; so they have to rely on some mechanic workshop or mechanical to tell them what problems they've encountered with their vehicle but only once its repaired. Considering most mechanics / repair shops repair OBD-II errors by substituting parts until the cause of the problem is  solved. Merely because they don't even understand the workings of OBD-II well enough to pinpoint problems with any great success. For most of us, this type of hit-&-miss approach comes as an un-bugeted expense, which most car owners can ill-afford especially after having to pay the exorbitant rollback cost.

I believe there are thousands more vehicle owners today, interested in their own vehicle's maintenance and there are even more inclined towards DIY repairs than ever before because of ODB-II. Their motivating factor being the high cost of automotive repairs vs the low cost of ODB-II diagnostic scanners. Albeit that the lower cost scanners bordering on cheap doesn't do such a fantastic diagnostic scan as their more expensive counter parts. 

NEW GENERATION CARS

Hopefully, the next generation of automobiles will be released with onboard diagnostic scanners incorporated directly into the vehicle's infotainment system. Seeing that these fancy units are comprised of  several discrete devices built into the same platform.  It's quite common for the average touch screen infotainment systems to have features ranging from  Built-in Bluetooth to Built-in WIFI which supports WiFi hot-spot broadcasting. Integrated phone connectivity for calls. Some even have rear view camera support. 

Others have fully fledged full-format 1080P video decoding, and USB functionality with multi-format audio and multi-band radio, coupled to dedicated dual voice-coil subwoofer and surround sound speakers. Not to mention Internet APP download capability.  Some include mirror and link for both Android and IOS Phones and a Global Positioning System (GPS) for navigation. All thanks to the magic of powerful multi-core processors and microprocessor embedded systems. 

I'd say adding an OBD-II scanner in place of one of these gadgets would be more beneficial 
So, throwing in a pretty decent quality OBD-II scanner into such a menagerie of tech wouldn't be such a biggie for car manufacturers and the cost wouldn't be prohibitively expensive either.  But since we not at that point in automotive evolution as yet, most DIY car owners have to rely on the handheld / smartphone diagnostics to scan their cars. 

Be that as it may. Very fortunately there are some common fault lists that would prevent you from having to go buy an expensive OBD-II scanner or go through the agony and trauma of having your car fixed by trial and error. Sharing  common automotive problems for the benefit of other, who are bound to experience the exact same problems in the very near future is a godsend.  Same model cars tend to have the same problems as others but invariable and inevitably those components will fail because obsolescence was part of its initial design. The same components used different model cars tend to fail in the same way and cause the same problems.

We've found that the most common OBD-II problems are associated with misfiring engine cylinders, problematic exhaust Gate Reticulation system (EGR), Oxygen Sensor (O2), Electrical Harnesses and fault Catalytic Converters. Many car owners are decating their diesel models, claiming better performance. But since OBD-II was explicitly introduced to control and reduce carbon emissions, removing it is not such a great idea. 

Genuine Volkswagen Audi  Harness - 1KD971658
VW / Audi Harness ES#: ES2993475  
 

COMMON FAULTS 

Erratically idling, or misfiring of bucking or  car goes into limp mode or starts and cuts out all result any one or more of the following error codes:-

P0105 - Manifold Absolute Pressure / Barometric Pressure Voltage supply
P0106 - Manifold Absolute Pressure / Barometric Pressure out of range 
P0107 - Manifold Absolute Pressure / Barometric Pressure Low Input
P0108 - Manifold Absolute Pressure / Barometric Pressure High Input
P0234 - Turbocharger Overboost Condition Control limit exceeded
P0235 - Turbocharger Boost Sensor (A) Control circuit  limit not reached
P0236 - Turbocharger Boost Sensor (A) circuit  out of range
P0237 - Turbocharger Boost Sensor (A) circuit  Low Input
P0238 - Turbocharger Boost Sensor (A) circuit  High Input
P0243 - Turbocharger Wastegate Solenoid (A) Open/Short Circuit to Ground
P0245 - Turbocharger Wastegate Solenoid (A) Low Input/Short to ground
P0246 - Turbocharger Wastegate Solenoid (A) High Input/Short to B+
P1154 - Manifold Switch Over Malfunction
P1155 - Manifold Absolute Pressure Sensor Circuit Short to B+
P1156 - Manifold Absolute Pressure Sensor Circuit Open/Short to Ground
P1157 - Manifold Absolute Pressure Sensor Circuit Power Supply Malfunction
P1158 - Manifold Absolute Pressure Sensor Circuit  out of range
P1400 - EGR Valve Circuit  Electrical Malfunction
P1401 - EGR Valve Circuit  Short to Ground
P1402 - EGR Valve Circuit  Short to B+
P1403 - EGR Flow Deviation
P1404 - EGR Flow Basic Setting not carried out
P1406 - EGR Temperature Sensor Performance range
P1407 - EGR Temperature Sensor Signal too Low
P1408 - EGR Temperature Sensor Signal too High
P1511 - Intake Manifold Changeover Valve - Electrical circuit malfunction
P1512 - Intake Manifold Changeover Valve Short circuit to B+
P1513 - Intake Manifold Changeover Valve2 Short circuit to B+
P1514 - Intake Manifold Changeover Valve2 Short circuit to ground
P1515 - Intake Manifold Changeover Valve Short circuit to ground
P1516 - Intake Manifold Changeover Valve - Open circuit 
P1520 - Intake Manifold Changeover Valve2 - Open circuit 
P1521 - Intake Manifold Changeover Valve2 electrical circuit malfunction
P1553 - Barometric/manifold pressure signal ratio out of range

Polo Highline 1.9 TDI (9N) 2005
16621 - Manifold Pressure / Boost Sensor (G31): Signal too Low
P0237 - 000 - -

Audi A5 (8T0) 2012 
4166 - Manifold Pressure / Boost Sensor (G31)
P0238 00 [039] - Signal too High

Audi TT 1.8L R4/5VT 
16622 - Manifold Pressure / Boost Sensor (G31): Signal too High
0238 - 35-00 - 

000568 - Manifold Pressure / Boost Sensor (G31): Signal too High
P0238 - 001 - Upper Limit Exceeded - MIL ON

Passat 2.0T R4/4V TFSI 2006 
000568 - Manifold Pressure / Boost Sensor (G31): Signal too High
P0238 - 001 - Upper Limit Exceeded - MIL ON

VW Touran 1.9 TDI
P0236 - Manifold Pressure/Boost Sensor (G31) - Range/Performance Problem/Implausible Signal
Malfunction Indicator Lamp (MIL)(K83) active.

VW Golf 7 1.6TDI 
16622 (P0238 ) - Manifold Pressure/Boost Sensor (G31): Signal too High
16618 (P0234) - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)

Passat 2.0T R4/4V TFSI 2006 
004759 - Pressure Drop between Turbo and Throttle Valve
P1297 - 001 - Upper Limit Exceeded

This MAP Manifold Pressure Sensor aka Boost Sensor aka Thrust sensor  aka G31 is just a  thermistor. Essentially a resistor of a special kind, with the ability to change its resistance  subject to its surrounding temperature, hence the term thermistor is just a  word combination of "thermal" and "resistor".  However G31 sensor may not be fault but rather the wiring harness. Due to the constant engine heat, the harness wiring gets hard and becomes brittle resulting in poor contact, short and open circuits. 

FYI - Thermistors essentially come in two varieties, viz NTC (negative temperature coefficient) and a PTC (positive temperature coefficient). You can quite simply use an ohmmeter to measure the resistance of the thermistor. Then by bringing a hot soldering iron  tip close to the thermistor, its resistance would change in response to the soldering iron's radiated heat. When the resistance increases its a PTC and an NTC when the resistance decreases.  Much like discrete component resistors that are colour coded, thermistors leads are also colour coded which identifies the temperature range they operate at.

CATALYTIC CONVERTER

Catalytic Converter have become a hot topic of late. Thieves are stealing Catalytic converters from parked cars at night. However the Polo Highline 1.9 TDI is known to be troublesome. The main reason for  this being, use of poor quality diesel (500ppm as opposed to 50ppm or even 5ppm) and irregular oil changes  which caused soot build-up to block the performance of the catalytic converter, which in turn may lead to turbo failure.  So its fair to say that it's  not uncommon to remove/replace blocked catalytic converters  to prolong the life of the turbo itself.

However if it's not the Catalytic converter itself causing the above error,  it very possibly not the sensor either even though the diagnostic software may indicate that.  I'd say rather check, repair or replace the wiring harness to the Boost Pressure Sensor (G31) and also check wiring to the Intake Air Temperature Sensor (G42).  See my previous blog post https://volkswagen-polo-highline.blogspot.com/2015/03/wiring-harness-issues.html 

The diagnostic scanners may also thow the following errors in conjunction with the error above,  which could be caused by a leak in Air Intake and or Exhaust

16490 - Manifold / Barometric Pressure Sensor (G71) / (F96): Implausible Signal
P0106 - 35-00 - -

18000 - Altitude Sensor / Boost Pressure Sensor: Implausible Correlation
P1592 - 000 - -

Diesel engines are quite different from petrol engines in the sense that  the diesel engine is not variable in speed or power by controlling the air entering the engine as we do with the  throttle body in petrol styled engines. Feedback from Catalytic converter in petrol engines are also used to adjust the short term and long term fuel trim. Implying that petrol cars also have turbo boost errors due to the cat and intake and exhaust sensors.

16485 / P0101 Mass Air Flow Sensor (MAF) (G70) = Circuit Signal Implausible (out of range)
16497 / P0113 Intake Air Temperature  Sensor-1 (G42) = Signal too High
16515 / P0131 O2 (Lambda) sensor low voltage =  Bank-1 Low Voltage
16584 / P0200 Injector circuit =   Injector Circuit electrical fault
16620 / P0236 Turbo / Manifold Pressure Boost Sensor (G31) = Signal Implausible (out of range)
16622 / P0238 Turbo / Manifold Pressure Boost Sensor (G31) = Signal too High
16683 / P0299 Turbo Boost Pressure Reg = Control Range not reached (underboost) /mechanical fault
16785 / P0401 Exhaust Gas Recirculation (EGR) = Insufficient Flow (blocked)
17055 / P0671  Glow Plug/Heater Cylinder 1 (Q10)  electrical fault, open circuit 

17958 / P1550 code = Charge Pressure Control Deviation
Check for air leaks on both intake or exhaust side 
Turbocharger - check for whining engine and exhaust smoke
Charge Air Pressure Sensor faulty  - check connection to one of the the intercooler pipes
Wastegate Regulator N75 Valve  faulty  - Check one of the 3 thin hoses for leaks

18534 / P2102 Throttle  Actuator Control Motor = Signal too Low, check voltage to accelerator pedal 
18675 / P2243 O2  Sensor Reference Voltage Bank 1, open circuit 

___________________________________________________________________

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