KNOCK SENSOR

VAG KNOCK SENSOR K1 AND THE EPC LIGHT

VW, Seat, Skoda  and Audi Knock sensors have become quite notorious for sending the car into "limp mode". Limp mode is a safety feature on all Drive by Wire vehicles, implying an EPC-electronic power control-but no accelerator cable. EPC implies torque control. By analogy,  its something like a horse that gets spooked and takes off at high speed and out of control with its rider unable to rein him in,  or a frayed accelerator cable that becomes stuck while driving at high speed. That's just a recipe for disaster. Imagine stepping on the brake pedal but the high revs of the engine just forces the car forward, smoke pouring from the brake pads to the point that the become glazed and  no longer has any effect. Pushing the transmission into neutral isn't an option because without the load, the engine is destined to blow, perhaps even push a piston  through the side of the engine lock.  Drive by wire prevents this from happening and cuts power to the powertrain if it detects a fault that puts the engine at risk. Knock reacts somewhat similar to backfire since both are due to detonation and pre-ignition-incomplete combustion.

Detonation is a common problem associated with lean fuel mixture -non stichometric-and torque. The EPC light is often triggered on an incline when the torque is insufficient to pull the car uphill when in an inappropriate gear. Knock sensors can detect combustion knocks in individual cylinders. Knock sensor 1 (G61) senses cylinders 1 & 2, and knock sensor 2 (G66) senses cylinders  3 & 4. To prevent combustion knock, the ECU cylinder selective knock control overrides the electronic control of the ignition timing by retarding the timing, but may not be unable to if the Fuel Octane is too low causing secondary combustion in the cylinder. Knock sensor 1 (G61) is known to trigger EPC light and activate limp mode, hence it needs to be checked for flush engine contact and correct torque. DTC  P0171 and P0174 could show up in scans.

The ECU calculates engine ignition timing based on input signals from Throttle Position (TP) Sensor G79 and  Accelerator Pedal Position G185, the  Engine Speed (RPM) Sensor G28,  the load signal from Mass Air Flow (MAF) Sensor G70, the signal from the Throttle Valve Control Module J338,  the Coolant Temperature (ECT) Sensor G62, both Knock Sensors G61, G66 (additional G198 & G199 on V6, W8 & W12 engines) and signals from Camshaft Position Sensors G40, G163, (additionally G300, G301 on V6, W8 & W12 engines) When the engine is below 40 degrees  celsius knock sensors signals are not used to make timing decisions. What this implies is that when the EPC light turns on  when the engine is still cold, the knock sensors are not guilty , neither  the the Mass Air Flow (MAF) Sensor G70 nor the Coolant Temperature (ECT) Sensor G62 since whilst idling, have nothing to do with torque. That leaves the Accelerator Pedal with G79 & G185, the Throttle  Control body senders G187 & G188,  the  Engine Speed Sensor G28,  Camshaft Position Sensors G40 & G163 as the EPC limp mode culprits. However sensors are fairly reliable but the wiring  harnesses  are  more likely to be the cause of the problem, see wiring in Audi.

Fuel pressure regulator valve N276, the wastegate bypass regulator valve N75 and the  Ignition Coil N, N128, N158, N163 and its Power Output Stage N122 are three  more EPC culprits. Injectors N30-N33 can also cause the EPC light to turn on and cause car to go into "limp mode" but also causes the engine not to run smoothly. Once again before condemning the sensors or actuators, check the wiring harnesses to them.



EPC light
Epc light?
EPC light on
EPC light problem
EPC warning light?
EPC and ESP Problems
EPC and ABS warning lights on
EPC warning light, advice welcome
EPC Light and stalling
EPC what does this mean?
Epc Light that keeps coming on
EPC light and starting issues
EPC light come on frequently
EPC light pain in my butt
Epc Light On Power Loss
EPC warning light - car shakes violently - ideas?
EPC light & locked in Park. 2006 A6, need solution.
EPC light / Check Engine light - Audi not finding issue
EPC light came on and can't start the engine
EPC light coming on and difficulty starting
EPC warning light and stalling in traffic
EPC warning light is on the dash and another lamp
EPC light came on and there was lots of shudder
EPC light has just come on and doesn't go away
The EPC light came on and I had sluggish power
The EPC warning symbol came on today while driving.
The EPC warning light has been triggering fairly regularly
The warning light EPC does not go out or comes on or flashes
Occasionally the EPC light comes on
EPC Light comes on at 4000 rpm - clears on restart
EPC warning light?? 15 Nov 2011
EPC Light comes on at 4000 rpm - clears on restart 3 Mar 2011
My EPC and CEL (Check Engine Lamp) is on
My EPC light is now light on the dash
My EPC light goes on/off on a daily basis
My check engine light and EPC light is on
My Audi's epc light came on this morning
My epc light and check engine light came on
My EPC light came on then I tried to start the car but nothing happened
What is the EPC warning light?
what's the mean of epc light, when it's come on ?
When I start the car the EPC light on the dashboard stay on
when epc light's come on, car loosing power
What is epc warning light mean on a seat ibiza
Check Engine Light & EPC Light came on
When you try and accelerate the EPC light comes on and the throttle cuts out
Why does the epc light keep coming on in my audi a4
A4 with EPC light, stalling at dangerous times
Audi Q7 EPC engine management warning light
I have EPC warning light and acceleration problems
I'm having a problem with the EPC light on my 2003 Audi A4 2.0FSI
I keep getting the epc light come on
j'ai le voyant EPC qui reste allumé
Having EPC problems with a skoda fabia 1.4
Seat Leon 52 plate EPC light
Seat ibiza 1.2 EPC and Engine light on
Seat Ibiza EPC light on and acceleration problem?
Fabia EPC Light on
Seat arosa EPC light?
How do I reset a Seat Arosa EPC light?

The above EPC errors are common to Volkswagen, Audi, Skoda and Seat. The  VW, the 4motion, the Amarok, the new Beetle, the Bora, the Caddy, the Corrado, the CC, the Eos, the Fox, the Golf, the Jetta, the Kombi, the Lavida, the Lupo, the Passat, the Polo, the Phaeton, the Routan, the Santana the Scirocco, the Sharan, the Tiguan, the Touran, the Touareg, the Transporter, the Vento , the Up and lastly the Vivo. The Audi A1, A2, A3, A4, A5, A6, A7, A8, the Q3, Q5, Q7, the RS4, RS6, RS8, the R8, the S4, S6, S8, Audi TT. The  Seat Alhambra, the Altea, the Arosa, the Cordoba, the Ibiza, the Inca, the Leon, the Mii and the Toledo,  Skoda  Felicia, the Octavia, the Fabia, the Superb, the Roomster, the Yeti, the Rapid and the Citigo. The Audi RS-6, A4 Fsi, Audi A4, Audi S3, Audi TT, Audi R8, audi a4 2.8 quattro 5 speed, Skoda fabia, seat leon, seat ibiza, Avant RS 2, Coupé, Audi A3 Mk1, Volkswagen Golf Mk4, Volkswagen New Beetle, Volkswagen Bora/Jetta Mk4, SEAT León Mk1, SEAT Toledo Mk2, Škoda Octavia Mk1,  TFSI, FSI, GTI, TDI, 

INTERMITTENT IMPLAUSIBLE

VW POLO 9N HIGHLINE

The VW Polo comes in three flavours viz. the 9N1, 9N2 and the 9N3, dating from 2002-2009.  The Skoda Fabia and the Seat Ibiza/Cordoba share many of the 9N trates but omit Address 25 since all their onboard control module functions are not identical. In the case of the VW Polo, it shares the coding in Address 17 with Address 25 because they are linked, but this applies morso to the 9N3. However, the easiest way to recognised the 9N and its clones, are by the 6Q0, 6Q1, 6L0, 6N0 and 6R0 modules which are also populated in the Polo 6N range. The interesting thing is that even though some module are the same in both its hardware and software, they have different codings specified. 

It is understandable, since the coding value is subject to the collective components fitted because the coding is a sum of the binary value applicable to the individual components. This can be seen in the three scans below. Be that as it may, module coding seems to be a huge problem with most vehicle owners who do their own repairs, however I have also seen qualified mechanicians struggle for days to get a car back to its readiness state. The status chart below is what every VAG driver / owner desires from their vehicle, but  is often totally elusive.

01-Engine -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
15-Airbags -- Status: OK 0000
17-Instruments -- Status: Status: OK 0000
19-CAN Gateway -- Status: Status: OK 0000
25-Immobilizer -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
56-Radio -- Status: OK 0000

Readiness: 0 0 0 0 0  / Gata de funcþie: 0 0 0 0 0 / Tests passés: 0 0 0 0 0

VCDS FAILED READINESS SETTING

What I have found, is that when a component that contributes to the module coding value malfunctions, the scan reads "1 Fault Found: 01044 - Control Module Incorrectly Coded" but if the malfunctioning component is first repaired or replaced, and the fault is cleared, the  01044 code does not return since the checksum of the module is once again correct. Many vehicles owners see this 01044 code and start changing module codes, normally just to see what happens. But, and a big but at that, before I continue, I need to stress that it's imperative to print out a scan of the faults and the module codings before any repairs are attempted, so that, if there is a problem, you can always revert back to the original coding. Failure to so could incapacitate your car until it can be correctly re-coded which could be both time consuming and expensive. Implausible and Intermittent (implausible  intermittent signal) problems on VAG cars are rife or rather intermittent and implausible  (implausible  intermittent signal)  problems on all cars are rife ever since control modules were introduced. The main reason for this is bad, poor or intermittent electrical contact, especially  considering the vast increased in the number of multi-pin plugs and sockets and edge connectors. Because vehicles move,  the  forces on the electrical connections constantly changes and that's besides the expansions caused by heat and the contractions caused by cold, and the corrosive effect of the weather on vehicles. Hence intermittent problems in all languages abound. What follows is just a sampling of the intermittent and implausible (implausible  intermittent signal) error codes we could encounter.

01314 - Engine Control Module
013 - Check DTC Memory - Intermittent

00816 - Sensor für Lenkhilfe
30-00 - Unterbrechung / Kurzschluß nach Plus

00716 - Air recirculation Flap Positioning Motor (V113)
000 -  -  - Intermittent

01336 - Bus de données Groupe Confort
80-00 - en mode fil unique

004506 - Fuel Pressure Sensor (G247)
P119A - 000 - Malfunction - Intermittent - MIL ON

01596 - Servomoteur de volet d´air frais/air recyclé (V154)
30-10 - Rupture/court-circuit au pôle + - Intermittent

01336 - Data Bus for Comfort System
80-10 - Single-Wire Operation - Intermittent

01271 - Stellmotor für Temperaturklappe (V68)
000 - - - Sporadisch

00588 - Airbag Igniter; Driver Side (N95)
32-10 - Resistance too High - Intermittent

00778 - Steering Angle Sensor (G85)
49-10 - No Communications - Intermittent

00706 - Relais de ventilateur de radiateur V7 et V35 -vitesse 2 (J513)
009 - Rupture/court-circuit à la masse - Intermittent

00896 - Closing unit tailgate (F256)
27-10 - Implausible Signal - Intermittent (implausible  intermittent signal) ----------

00576 - Klemme 15
002 - unterer Grenzwert unterschritten - Sporadisch

01312 - Powertrain Data Bus
37-10 - Faulty - Intermittent

00-Senzor unghi volan -- Status: OK 0000
01-Motor -- Status: Malfuncþie 0010
03-ABS frâne -- Status: OK 0000
08-Clima automatã -- Status: OK 0000
09-Electronica centralã -- Status: Malfuncþie 0010
15-Airbaguri -- Status: OK 0000
16-Electronicã volan -- Status: OK 0000
17-Instrumente bord -- Status: OK 0000
19-Poarta CAN  -- Status: Malfuncþie 0010
25-Blocare pornire -- Status: OK 0000
42-Uºa electr. ºofer -- Status: OK 0000
44-Asistenþã direcþie -- Status: OK 0000
46-Confort -- Status: Malfuncþie 0010
52-Uºa electr.pasager -- Status: Malfuncþie 0010
56-Radio -- Status: OK 0000
69-Tractare -- Status: Neautorizat 0001
76-Asistenþã parcare -- Status: OK 0000
7D-Încãlz. Aux. -- Status: Malfuncþie 0010

VW JETTA WIRING HARNESS

However,  we all desire the following messages from our cars:-  Aucun code défaut trouvé. No fault code found. Kein(e) Fehlercode(s) gefunden. Nu a gãsit coduri.  The wiring harness of all cars are made with flexible multicore wire with terminal connectors and clip-lock plugs to facilitate connection durability when driving on bumpy roads and uneven surfaces but it seems that shaking, vibration, heat, shafting and corrosion are responsible for the above errors which would probably not resulted if there were not as many interconnected sub harnesses, and multi-pin electrical connections. Volkswagen  vehicles wiring harnesses have undergone a huge technological evolution since 1984. So much so that  30 years later the average wiring harnesses has become extremely complex because the number of terminals have progressively increased from a typical 200 terminals in a 1994 vehicle to as many as 1,400 terminals in the latest models.

The cost implications of these new wiring harnesses and electronic modules constitute more than a quarter of the price of the cars. It is estimated that it takes approximately one and a quarter hours to completely assemble and engine on a production line, whereas it takes more than 5 hours to assemble a wiring harness. Since the complexity of wiring harnesses  escalated exponentially, it is only obvious that the time and cost associated with repairing wiring harness would increase considerably. Thinner wires are used carrying extremely low-level signals and data, interlinked electronic control modules, sensors and actuators communicating in several protocols, collectively resulting in limited access and mass confusion. Restated, automotive repairs have become lot more complicated and it is estimated that almost half of all warranty repairs are caused by electrical malfunctions, and approximately 30 percent of all tow-ins, are due to problems associated with the wiring harness.

This emphatically tells us that the wiring harness is no longer a collection of wires and connectors bound together, because each and every length of wire, connection,  twist and turn, is carefully engineered to suit the application and its environment. Therefore whenever electrical harness repairs become necessary, don't use shortcuts and offcuts pieces of wire from an old extension lead or solid wire from domestic electrical cable and solder joints. Solder joints will eventually break due to vibration and spirited driving. Use the appropriate motor grade multicore flexible wiring of the appropriate diameter with the correct terminals and the appropriate electronic modules and components to restore the wiring harness to its original integrity because failure to do so, will only result in more intermittent and implausible (implausible  intermittent signal) contacts. To give you some idea of the wiring harness complexity I have included the numbers of the various sub harnesses that constitute the entire harness for my car.

WIRING HARNESS

VW Polo Highline 2.0L wiring harness  numbers ( Teilenummern ZSB- Leitungsstrang)

6Q2 970 005 DH, 6Q2 970 006 Q, 6Q2 970 010 L,  6Q2 970 024 H,
6Q2 970 076 AB, 6Q2 970 091 H, 6Q2 970 099 E , 6Q2 970 106 RB,
6Q2 970 111 D,   6Q2 970 154 C, 6Q2 970 191 D,  6Q2 970 083 CJ,
6Q2 970 050 P,    6Q2 970 125 K, 6Q2 970 102 RQ,  6Q2 970 023 CD,
6Q2 970 003 L,    6Q2 970 049 F, 6Q2 970 000 RQ,   6Q2970 030 AA
6Q2970 012 CN,

The underlined 6Q2 970 049 F above is the Cent. Elect. Controller 0009 BN-SG.   2S36 siting at Address 09,  the rest are individual harnesses or rather interconnecting parts of a whole harness.

SCANS

Chassis Type: 9N1 - VW Polo
Scan: 01,02,03,08,09,15,17,19,37,44,46,56,69

Address 01 -------------------------------------------------------
Controller: 032 906 032 E
Component: ME7.5.10 *2503
Coding: 00071

Address 03 -------------------------------------------------------
Controller: 6Q0 907 379 AF
Component: ABS 8.0 front H03 0002
Coding: 0002175

Address 08 -------------------------------------------------------
Controller: 6Q0 820 045
Component: Klimaanlage X0840

Address 09 -------------------------------------------------------
Controller: 6Q0 937 049 D
Component: À0_0 BN-SG. 1S34
Coding: 25742

Address 15: ------------------------------------------------------
Airbags
Controller: 6Q0 909 605 AE
Component: 0H AIRBAG VW5 0C 0010
Coding: 12360

Address 17 -------------------------------------------------------
Controller: 6Q0 920 823 B
Component: KOMBI+WEGFAHRSP VDO V02
Coding: 00141

Address 19 -------------------------------------------------------
Controller: 6N0 909 901
Component: 0000 GATEWAY CAN 1S34
Coding: 00014

Address 44 -------------------------------------------------------
Controller: 6Q0 423 156 AB
Component: LenkhilfeTRW V270
Coding: 10140

Address 46 -------------------------------------------------------
Controller: 6Q0 959 433 E
Component: 67 Komfortgerát 0002
Coding: 00018

Address 56 -------------------------------------------------------
Controller: 6Q0 035 186 A
Component: Radio FF6 0001
Coding: 00401

End -------------------------------------------------------


Fahrzeugtyp: 9N - VW Polo
Scan: 01 02 03 08 09 15 17 19 25 37 44 45 46 56 76

Adresse 01: -------------------------------------------------------
   Motor
   Teilenummer: 03D 906 023
   Bauteil: SIMOS91 1.2l 2V     5415
   Revision: --H04---    Seriennummer: VWZ5Z0G8041219
   Codierung: 0000071
   Betriebsnr.: WSC 00810 219 84798
 
Adresse 03: -------------------------------------------------------
   Bremsen  
   Teilenummer SW: 6Q0 907 379 AF    HW: 6Q0 907 379 AF
   Bauteil: ABS 8.0 front   H05 0002
   Revision: 00000000    Seriennummer: 00000000000000
   Codierung: 0002082
   Betriebsnr.: WSC 00788 785 00200

Adresse 08: -------------------------------------------------------
   Klima/Heizung  
   Teilenummer: 6Q0 820 045
   Bauteil: Klimaanlage        X0850

Adresse 09: -------------------------------------------------------
   Bordnetz      
   Teilenummer: 6Q1 937 049 F
   Bauteil: 0009 BN-SG.         2S36
   Codierung: 25742
   Betriebsnr.: WSC 00788
 
Adresse 15:  -------------------------------------------------------
   Airbag      
   Teilenummer: 1C0 909 605 K
   Bauteil: 19 AIRBAG VW51 0P   0010
   Codierung: 12601
   Betriebsnr.: WSC 00788
 
Adresse 17: -------------------------------------------------------
   Kombiinstrument    
   Teilenummer: 6Q0 920 804
   Bauteil: KOMBIINSTRUMENT AGD V04
   Codierung: 01131
   Betriebsnr.: WSC 00000
 
Adresse 19: -------------------------------------------------------
   CAN-Gateway      
   Teilenummer: 6N0 909 901
   Bauteil: 01K1 GATEWAY CAN    2S36
   Codierung: 00014
   Betriebsnr.: WSC 00788
 
Adresse 25: -------------------------------------------------------
   Wegfahrsperre
   Teilenummer: 6Q0 920 804
   Bauteil: IMMOBILIZER     AGD V04
   Codierung: 01131
   Betriebsnr.: WSC 00000
 
Adresse 44: -------------------------------------------------------
   Lenkhilfe    
   Teilenummer: 6Q0 423 156 AB
   Bauteil: LenkhilfeTRW        V270
   Codierung: 10140
   Betriebsnr.: WSC 00788
 
Adresse 46: -------------------------------------------------------
   Komfortsystem    
   Teilenummer: 6Q0 959 433 E
   Bauteil: 3F Komfortgerát     0002
   Codierung: 00019
   Betriebsnr.: WSC 00788
 
Adresse 56: -------------------------------------------------------
   Radio      
   Teilenummer SW: 6Q0 035 152 G    HW: 6Q0 035 152 G
   Bauteil: Radio DE2           0007
   Revision: 00005000    Seriennummer: VWZ4Z4G3272350
   Codierung: 0020200
   Betriebsnr.: WSC 00788 785 00200
 
Ende -------------------------------------------------------

Type chassis: VW Polo 9N
Scanner: 01 02 03 08 09 15 17 19 37 44 45 46 56 76

Adresse 01: -------------------------------------------------------
Moteur
No. pièce: 038 906 019 NC
Pièce: 1,9l R4 EDC 0000SG 6138
Codage: 00002

Adresse 03: -------------------------------------------------------
Freins ABS
No. pièce Log: 6Q0 907 379 AF Mat: 6Q0 907 379 AF
Pièce: ABS 8.0 front H05 0002
Révision: 00000000 No. de série: 00000000000000
Codage: 0002193

Adresse 08: -------------------------------------------------------
Climatronic
No. pièce: 6Q0 907 044 E
Pièce: CLIMAtronic PQ24 3805

Adresse 09: -------------------------------------------------------
Centrale Elec.
No. pièce: 6Q1 937 049 F
Pièce: 0009 BN-SG. 2S36
Codage: 09870

Adresse 15: -------------------------------------------------------
Airbags
No. pièce: 1C0 909 605 K
Pièce: 17 AIRBAG VW51 0N 0010
Codage: 12599

Adresse 17: -------------------------------------------------------
Instruments
No. pièce: 6Q0 920 825 H
Pièce: KOMBIINSTRUMENT VDO V06
Codage: 01141

Adresse 19: -------------------------------------------------------
Gateway CAN
No. pièce: 6N0 909 901
Pièce: 01K1 GATEWAY CAN 2S36
Codage: 00014

Adresse 44: -------------------------------------------------------
Direction assistée
No. pièce: 6R0 423 156
Pièce: LenkhilfeTRW V272
Codage: 10120

Adresse 46: -------------------------------------------------------
Module confort
No. pièce: 6Q0 959 433 E
Pièce: 5F Komfortgerát 0002
Codage: 00017

Adresse 56: -------------------------------------------------------
Radio
No. pièce Log: 6Q0 035 152 E Mat: 6Q0 035 152 E
Pièce: Radio 9NK 0004
Révision: 00001000 No. de série: VWZ4Z4H0100621
Codage: 0040400

End -------------------------------------------------------

Feel free to upload your VW, SKODA, SEAT & AUDI scans.

Adresse, Address,  Betriebsnummer, WS Code, Control Module for Airbags, Control Module for Climatronic, Control Module in Instrument Cluster, Power Steering Control Module, Engine Control Module, Data Bus for Comfort System, Coding, Control Module for Digital Sound Package, No Signal/Communication - Intermittent, Intermittent Operation, Defective - Intermittent, Open Circuit — Intermittent, Short to Ground — Intermittent, Open or Short to Plus — Intermittent, Implausible Signal — Intermittent, No Communications - Intermittent, Electrical Fault in Circuit - Intermittent,

EPC LIGHT - REVISITED

VW POLO EPC LIGHT 

Most VW Polo, Golf, Audi, Passat and  Skoda  vehicles and probably every other VAG cars appears to have problems lately. In one sentence, the most common of these problems seems to be on obd diagnostics the culprit being the  wiring that interconnect all the electronic modules, aka the OBD II / CANbus. Virtually every car diagnostic test done on several different VAG cars produced the same faults. This implies that they are common, since they are recurring on different owners cars.  I can relate to this from my Television engineering days, when several same-make and same-model televisions all appeared to give the same problems. These VAG cars all seemed to have Intermittent / Implausible messages on the Data Bus and its highly unlikely that it could be the electronic modules themselves that are intermittent. Should this be the case, each and every one of these VAG cars then needs to be recalled because it looks like a defective design or assembly line problem.  But that's  wishfully thinking on my part which will obviously be met with and answer like - highly unlikely.

Wiring harnesses and cable assemblies for electrical buses interconnecting several MOSFET fast switching electronic modules each having an edge connector / plug whether it is gold plated or not, has parasitic capacitance. Add this  to the edge connector resistance and crimped wire contacts inside the plugs makes for interesting intermittent connections. The following list are faults /errors  that showed up on diagnostic tests on cars with EPC light problems, which  gives you some idea what I'm referring to. I've  abbreviated "Powertrain Data Bus" to PDB: in order to stop each fault from running onto two lines. Excessive comms errors and internal control module memory error intermittent are common faults caused by wiring harnesses.

SCAN TOOL ERROR CODES

1) 01312 - Powertrain Data Bus:  - Faulty

2) 18034 - PDB: error P1626 Missing Message from TCU  (Transmission Control Unit)
3) 18043 - PDB: error  P1635 Missing Message from A/C Controller
4) 18044 - PDB: error  P1636 Missing Message from Airbag Controller
5) 18058 - PDB: error  P1650 Missing Message from Instrument Cluster
6) 18270 - PDB: error  P1862 Missing Message from Instrument Cluster 

7) 18055 - PDB: error  P1647 Check Coding of ECUs
8) 18056 - PDB: error  P1648 Failure
9) 18045 - PDB: error  P1637 Missing Message from Electric Load Controller
A) 18097 - PDB: error  P1689 Implausible Message from Elect. Load Controller

B) 18104 - PDB: error  P1696 Implausible Message from Steering Column Controller
C) 18107 - PDB: error  P1699 Missing Message from Steering Wheel Electronics

D) 18057 - PDB: error  P1649 Missing Message from ABS Controller
E) 18259 - PDB: error  P1851 Missing Message from ABS Controller
F) 18090 - PDB: error  P1682 Implausible Message from ABS Controller
G) 18261 - PDB: error  P1853 Implausible Message from ABS Controller

Implausible signal means that it is "intermittent", even intermittent at the time the diagnostic tester was interfacing with the ECU's, TCU's, STC's ABS's, A/C etc... "Missing Message" implies absolutely no contact (Open Circuit) with the respective modules at the time of testing. Since VAG cars became inundated with electronic modules, our individual cars each have a few hundred more electrical connections than the previous generation of cars each and everyone of them subject to the tresses and strains of  the bumps on uneven roads and spirited driving. Add engine heat, steam, dampness and other weather conditions to this equation and suddenly these connections become tarnished over time. Tarnished connections are certainly not electrically sound and one way to clean these contacts is with contact spray but graphite or a grey ink rubber would be more effective to clean the tarnish off the gold plated PCB edge connectors. The Bentely VW manual suggest replacement of the whole wiring harness if  any problems arise but it comes at a cost of  $798.00 and that's for a 2007 VW Polo highline. I would hate to know what it would cost for a 2013 Volkswagen Touareg or 2013 Volkswagen Amrok not to mention 2013 Audi A8 or Audi TT .

VAG cars are really nippy and a joy to drive and I'm certain the bulk of VAG car owners enjoy spirited driving but many many VAG car driver probably regret this since they only experienced  EPC light troubles after they did some real spirited driving. I know this is absolutely true for Audi TT drivers who complained that their cars were fin until they gave it a nice workout. It is obvious centrifugal force, torque, tension, flexing, wind resistance and inertia plays their respective roles on the plugs and connectors. The EPC Light problems above, D through G appears to dictate that the ABS Controller is faulty or its edge connector / plug is faulty or the harness is faulty. B through C suggest that the Steering Wheel Controller is faulty or its edge connector / plug is faulty or the harness is faulty is causing the EPC light  to light up. Numbers 5&6 seems to favour the Instrument Cluster as faulty or its edge connector / plug is faulty or the harness is faulty which causes the EPC light to light up. Number 9 and letter A seems to blame the Electric Load Controller for triggering the EPC light. Numbers 1-4 and 7&8 seems to suggest some other electronic module caused the EPC light to light up. All these modules have one thing in common, they are all associated with the Powertrain Data Bus. In essence any module associated with the Powertrain Data Bus can cause the EPC light on VW Polo or other VAG cars to trigger.

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