DIAGNOSTIC TROUBLE CODES

DIAGNOSTIC TROUBLE CODES

Your car has been misbehaving of late. Somehow she just doesn't seem to perform like she did in the past. It is very likely that there is a problem with your car and that she already threw an error code, now stored in its OBD (on-board Diagnostics) system. Fortunately this stored data can be retrieved via the diagnosis interface because diagnostic error codes have been standardized globally. Implying that the stored data can be retrieved with any Generic Scan Tool. Virtually every VW service center and even some private mechanics have one or more. Many private individuals have also invested in scan tools  because automotive repair cost have just skyrocketed of late hence they prefer to do the repairs themselves. I've been doing all my VW repairs for the past 8 years. 

OK, so now that youv'e done a diagnostic scan of your car, and retrieved the diagnostic scan codes, the printout looks like a foreign language. You desperately need help to understand what it means but you are no nearer to solving the misbehaving problem with the scan in hand, than you were without the scan. Don't worry, after explaining the basics of scan analysis, you will have a decent idea how to interpret your particular scan and perhaps even do the repair yourself before deleting / clearing the error code.

Low cost Diagnostic scan tools from various manufacturers.

Before we start to analyse the scan there are a few things that I need to mention. Diagnostic errors or more correctly DTC (diagnostic trouble codes) are numerous and fall into to categories, viz Generic fault codes / manufacturer-specific fault codes. However, there is a third category specific to VAG vehicles, though many mechanics also consider them as manufacturer-specific. But I will expound on this later. Fault code are divided into four categories viz, P, B, C and U One of these four alphabetical letters always precede  four numerals  and are thus referred to as an alphanumeric  code or just code for short. The P category is by far the most interesting. Both Generic fault codes and  manufacturer-specific fault codes are applicable to all OBD-II vehicles but manufacturer-specific fault code definitions vary from manufacturer to manufacturer and are also different to VAG codes.

P CODES

The P stands for powertrain, meaning the car's engine and gearbox / transmission.  So any and all preceded by a P is associated with engine or transmission problems. For example, P0100 is a powertrain code that correlates to  'mass  air flow circuit problem'. P0200 is also a powertrain code that correlates to an 'open circuit injector'. P0300 is a another powertrain code that correlates to the 'detection of random/multiple cylinder misfires'. P codes start at P0000 and range to P3999.  Generic P codes are a subset of P codes and start with either P0xxx, P2xxx and P34xx - P39xx, implying that P codes  staring at P1xxx and P30xx- P33xx are not generic but manufacturer-specific codes. 

As can be seen above, in the Powertrain system , the first digit after the P indicates  whether or not the code is generic or manufacturer-specific. The second digit identifies a specific area of the vehicle that's at fault. The powertrain components are divided into 9 distinct area as can be seen below. ( Refer to diagram below)

1xx Fault codes related to 'Fuel & Air Metering'
2xx Fault codes related to 'Fuel, Air metering & Injection Circuit'
3xx Fault codes related to 'Ignition System & Misfire Detection'
4xx Fault codes related to 'Auxiliary Emission Controls'
5xx Fault codes related to 'Vehicle Speed & Idle Control System'
6xx Fault codes related to 'Computer Output Circuit'
7xx Fault codes related to 'Transmission / gearbox related faults'
8xx Fault codes related to 'Transmission / gearbox related faults'
9xx Fault codes related to 'Transmission / gearbox related faults'

The third and fourth digits identify the specific component involved with the fault. This can be referenced from a complete list of codes that can be downloaded from various OBD sites. For example, www.outilsobdfacile.com/ www.obd-codes.com/trouble_codes/ www.launchtech.co.uk  www.trouble-codes.com/ www.automotive-technology.co.uk 

The fault code doesn't identify the actual component that's causing the fault but rather narrows it down the area that needs to be investigated. Often times the sensor that does the detection actually goes faulty. For instance, the crankshaft position sensor and camshaft position sensors are prone to failure, causing the engine to stall or  fail to start. 

OBD-II Diagnostic Trouble Codes Explained

B CODES

B stands for Body and includes the Air Bag and other mechanical / electronic components not associated with the engine and transmission/gearbox. For example, B0005 is a body error code and correlates to a 'park switch circuit malfunction'. B0530 is another body error code and correlates to a 'stuck fuel level sensor'.  Generic body trouble codes start with either B0xxx or B3xxx, again implying that B codes starting with B1xxx and B2xx are manufacturer-specific codes.

C CODES

C stands for Chassis and include the ABS and other mechanical / electronic components not associated with neither  the engine and gearbox nor the body. For example,  C0281 is a chassis error code and correlates to a 'brake switch circuit malfunction'. C0238  is a chassis error code and correlates to a 'wheel speed mismatch'. The generic network trouble codes for C start with  either C0xxx or C3xxx. C codes starting with either C1xxx or C2xxx are manufacturer-specific codes.

U CODES

U stands for User Network. Initially the U stood for “undefined” but is now network-related. For example,  U0109 is a network error code  and correlates to 'lost communication with fuel pump control module'. U0405 is another is a network error code  and correlates to 'invalid data received from cruise control module'. The generic network trouble codes for U start with  either U0xxx and or U3xxx, again implying that codes starting with U1xxx and U2xxx are manufacturer-specific codes. 

VAG CODES

Now VAG codes on the other hand  range from 00000-65535 and don't have any letters. It is just a 5 digit numeral and coincides with the list of both generic code and manufacturer specific codes. For example:-

VAG code 16385 coincides with generic code  P0001 - Fuel Volume Regulator Control Circuit Open

VAG code  16389 coincides with generic code  P0005 - Fuel Shutoff Valve (A) Circuit Open


VAG code   16434 coincides with generic code  P0050 - Oxygen Sensor Heater Bank 1/2 Control Circuit

Generic fault code P0403 equates to a VAG 16787 - EGR Valve Malfunction

Generic fault code P0571 equates to a VAG 16955 code - Brake Switch Signal Implausible 

Generic fault code P1690 equates to a VAG 18098 code - Malfunction Indication Light (K83)


Generic fault code  P1814 equates to a VAG 18222 - Transmission Pressure Control Valve open or Short to Ground 

Generic fault code P0032 equates to a VAG 000050 - Oxygen (Lambda) Sensor Heating Circuit Short to Plus 

Generic fault code P0720 equates to a VAG 17104 -  Transmission Output Speed Sensor (G195) Circuit Malfunction


Generic fault code P1517 equates to a VAG 17925 -  ECU Power Supply Relay  Malfunction 

Looking at your scan printout, especially if it's a VCDS scans, it may be quite evident that there are two or three data systems delivering the same data but in a slightly different format. The clipping below purely displays VAG codes with a numeric description.

Address 17: Instruments Labels: Redir Fail!
Part No: 6Q0 920 820 H
Component: KOMBI+WEGFAHRSP VDO V05 
Coding: 00141

6 Faults Found:
01312 - Powertrain Data Bus 
37-10 - Faulty - Intermittent
01314 - Engine Control Module 
49-10 - No Communications - Intermittent
01316 - ABS Control Module 
49-10 - No Communications - Intermittent
01321 - Control Module for Airbags (J234) 
49-10 - No Communications - Intermittent
01322 - Control Module for Multi-Function Unit (MFA) (J501) 
49-10 - No Communications - Intermittent
01309 - Power Steering Control Module (J500) 
49-10 - No Communications - Intermittent


The clipping below displays both generic and VAG error codes as well as a fault description in number code.

Address 01: Engine        Labels: 06A-906-032-BBW.lbl
Part No: 06A 906 032 RJ
Component: 2.0l R4/2V      G   6505  
Coding: 00003
   
4 Faults Found:
17837 - Circuit for Brake Vacuum Pump 
P1429 - 35-00 - Open Circuit
16452 - MAP/MAF  Throttle Position Correlation 
P0068 - 35-00 - 
16804 - Catalyst System; Bank 1 
P0420 - 35-00 - Efficiency Below Threshold
16395 - Bank 1: Camshaft A (Intake) 
P0011 - 35-10 - Retard Set point not Reached - Intermittent

The clipping below  shows VAG 5 digit codes and description numbers.

46 Address: Central Conv. Labels: 1C0-959-799.lbl 
Part No: 1C0 959 799 C 
Component: HLO Komfortgerát 1H 0003 
Coding: 00258 

3 Faults Found: 
01330 - Central Control Module for Central Convenience (J393) 
53-10 - Supply Voltage Too Low - Intermittent 
00849 - S-contact at Ignition / Starter Switch (D) 
25-00 - Unknown Condition Switch 
01359 - Internal Central Locking Switch; Passenger Side (E198) 
27-10 - Implausible Signal - Intermittent

As can be seen in two of the examples above, there are also numbers like, 27-10, 37-10, 49-10, etc. The first two digits of each set of numbers are the numeric equivalent to the text meaning 'Implausible Signal, 'Faulty  and 'No Communications' respectively. Each set of numbers ends in -10, which means 'intermittent'. Hence 27-10 means Implausible Signal - Intermittent, 37-10 means  Faulty - Intermittent and  49-10 means  No Communications - Intermittent. Fault codes can also have a -00 suffix in place of -10 which implies a definite fault (not intermittent). Occasionally you would encounter just a hyphen (-). This implies that the scan equipment could not retrieve further details about the fault and just left it blank. 

HOW TO STEAL AN AUDI

HOW TO STEAL AN AUDI, VOLKSWAGEN, SEAT OR SKODA

Gone are the days when car thieves could slim-jim a car's door, jam a screwdriver into the ignition lock and turn it with force to start the car, or alternatively cut the ignition wires and hot wire the car, and off they go. In most cases stolen cars are seldom recovered, forcing Insurance Companies to hike their premiums. Lobbying  on their part, and government efforts to reduce car theft, resulted that immobilizer and alarm systems started appearing as standard features in most cars.  I believer that it's now mandatory for all new cars sold within the European Union to have an electronic engine immobilizer installed.

IMMOBILIZER

An immobilizer acts as an anti-theft device that inhibits the car's engine from starting, unless the correct ignition key or additional electronic deactivation device is present. This concept makes hot wiring a car totally futile. If the code received from the key is incorrect or missing, the ECU disables the system until the correct key is placed in the ignition, and or the correct key code  is presented, which will allow the car to start. Such electronic devices operate  automatically and effectively prevents thieves from starting a car by hot wiring it, thus incentivising auto Insurance Companies to offer lower rates for vehicles equipped with these anti-theft devices. Be that as it may. Are immobilizers "secure" enough? Especially considering that it only reduced car theft by an estimated 40%. 

Transponder chips used in automotive immobilizer systems

Currently, electronic chips,  algorithms and data encryption systems are used to protect cars from theft. And since its inception, the electronics industry members have had ways of marking their micro chips. In most cases, with  an alpha numeric marking and perhaps a logo. Texas chips had a tiny map of Texas, Motorola had their classic M, Phillips  had an emblem composed of a globe with a doubly wavy equator with two stars in each hemesphere. There were also several other electronic chip manufacturers many of them specializing in specific equipment. But today Philips and Texas Instruments dominates the fob key transponder market with their immobilizer chips. Legacy key manufactures like JMA and Silca each formed in-house electronics departments that specifically focuses on transponder technology and vigarously compete for market share. Then there is also Sokymat, Temic, NXT, Megamos, etc, providing anti-theft transponder / immobilizer electronic devices for keys.

Turbo Key Decoder can unlock any VAG car in just 3 minutes.

A VW 3 button remote fob key fitted with a transponder and a miniature electronic circuit board essentially broadcasts an encrypted radio signal to the receiver fitted in the car's steering column, at the exact moment the driver starts the vehicle. If the signal is recognized by the receiver and the handshake is successful, it then responds by sending an encrypted signal to the car's engine control unit (ECU), enabling the car's engine to start. In Volkswagen vehicles, the miniature electronic circuit board in the fob key handles central lock/unlock and alarm activation which normally operates on the 433Mhz (UHF) frequency band, but some models  operate on either  315MHz or at 868MHz frequency band. 

Volkswagen, Audi and Seat only uses two key blade profiles, namely HU66 and HU49 on both their flat and flip keys, whereas the Skoda uses both HU66 HU49 and SK22 blade profiles. The blades and profiles are visible in the image below which can easily be decoded with a Turbo key decoder or a cheaper Lishi decoder, aka Master Key-Set for VAG for the relevant blade profile.

Volkswagen. Audi, Seat and Skoda key blade profiles.

The intricacy starts with the numerous transponders used in Volkswagen, Audi, Seat and Skoda which varies from the PHILIPS ID33 Transponder, to the PHILIPS Crypto ID42 Transponder, to the PHILIPS Crypto ID44 Transponder, to the PHILIPS Crypto ID46 Transponder,  to the MEGAMOS  ID13  Transponder and MEGAMOS Crypto  ID48  Transponder; to the Silca and JMA equivalents. Some  precoded  Megamos Crypto transponders can be coded from the VIN using the appropriate equipment, like the AD100Pro.

Megamos Crypto ID48 transponder (glass)

Having said appropriate equipment; immobilizers according to most of us are  "secure" but research hackers have found vulnerabilities in the engine immobilizers algorithm / encryption system that is supposed to protect the vehicle from theft.  Apparently said hacker hacked one of the most popularly used immobilizers  within a mere 6 hours.  He then released a white paper "Wirelessly Lockpicking a Vehicle Immobilizer" but was gagged by the High Court of London with an interim injunction from releasing his scientific article for public consumption. 

The following is an actual cryptographic hash (SHA-512) 

9d05ba88740499eecea3d8609174b444
43683da139f78b783666954ccc605da8
4601888134bf0c23ba46fb4a88c056bf
bbb629e1ddffcf60fa91880b4d5b4aca

Silicon chip transponder

What this means is that the current 48 bit encryption systems used by most car manufacturers can be easily cracked. The rolling code Hitag2  system used by Alfa Romeo, Chevrolet, Citroen, Dacia, Fiat, Ford, Lancia, Mitsubishi, Nissan, Opel, Peugot and Renault has been crack several years ago and is not secure. A 48 bit system is fractionally secure compared to the 128 bits Advanced Encryption Standard (AES) used for computer data systems which could take more than a 100 years to crack with a Quantum Super Computer. To add doom to gloom, several key decoders and key duplicators are available on the open market and you don't have to be a certified locksmith to be able to buy it, though they is quite expensive. 

"The mechanical turbo decoder can unlock any

 Audi, Volkswagen, Seat or Seat 

within 3 minutes flat".

Once the key is duplicated, the doors can be unlocked  and turning on the ignition is just as simple.  Starting the vehicles is slightly more intricate but still doable. Silca and JMA supplies systems that can do exactly that in just a few minutes. Optika, Lector and Lector Pro reads the code from the key and generates the required code.
What this means, is  that it now easier to steal a car with a manufacturer fitted immobilizer than a car with an anti theft gorilla bar attached to its steering.

Car Steering Wheel Theft proof Lock - Auto Anti-theft Retractable Lock

Laser key cutting machines  and key duplicating machines are as popular as diagnostic scanner software and it is really easy to use. I suppose its just a matter of time before crime syndicates  invest in these devices to further ply their "trade". Looks like Gorilla bars are back in vogue.