Accelerator pedal position sensor 1/2 - implausible signal for G79 + G185

Hello there,
I was really lucky to find this page, and I've already copied out a lot of information about a problem I'm familiar with. Unfortunately, my area of expertise is different, and I've only learned enough to be sure that my control unit was probably replaced unnecessarily. Unfairly charged to my account: €1471.91 for repairs + €359.00 for a replacement car.

Okay, so my problem started like this:

In February '03, just 2 weeks after the water pump failed at 80,000 km, also damaging the timing belt, my car broke down in Munich, shortly after I exited the highway, essentially in the middle of the road. The car wouldn't accelerate, the engine was running at 1200 rpm, and the glow plug preheating indicator was flashing. Two hours after the ADAC (German equivalent of AAA) arrived and towed me to a VW dealership, I had to leave my car there and take a replacement car to Erding. As always, it was on a Friday after 7:00 PM. The diagnostic error code was: "Sensor ½ for accelerator pedal position - G79 + G185, implausible signal." The car spent 3 days in the workshop, partly because the workshop failed to order the accelerator pedal potentiometer. Okay. Okay, I picked up the car, complained about the hefty bill, and paid it provisionally.

Self-diagnosis: Reading error codes - €16.20.
Pedal support A+E: 60.90
Pedal position sensor A+E: 40.50
Donation for ... €230.00
Pulley. 14.50
Mother: 0.19
Washer 0.08

So, in the end, it's €420.35.

A week later, with bad weather and snow. In the middle of the acceleration lane on the A99 East heading towards the A94, the car stopped again, without any gas. After waiting for hours for the ADAC (German Automobile Club), the hazard lights also broke down. When the ADAC arrived, the car started normally. We were able to drive for two more exits in the direction of Erding, but then the problem reappeared, repeatedly. However, the ADAC employee accompanied me all the way home. The next day, I immediately drove to the car dealership **** in Erding and explained my problem.

Subsequently, the car spent a week in the workshop, and the fault diagnosis remained the same.
The bill turned out to be even more expensive than the first one. €1471.91 for repairs + €359.00 for the replacement car.
After paying the first bill, I went to the VW dealership and requested a refund of €420, which I received. However, the cost of the replacement car was not reimbursed.

A few months and a car wash later, I emerged with the emergency mode still active, but at least freshly washed. All good. So, I drove back to the dealership. As always, it was Friday afternoon. The error code was read, confirmed to be the same, and then cleared. I was told to wait until Monday. Eventually, another control unit was installed, free of charge. I think I was happy (or maybe not) for a little over a year.

In the fall of 2004, sporadic errors reappeared. The pattern is always the same: once it occurs, the error happens at increasingly shorter intervals. My car spent another week in the workshop, and I was told that they replaced the wiring harness. At that time, I had the extended warranty, which was used to invoice the VW insurance company €660.06. The same thing happened again, and after that, I had some peace for a while. Also, during that time, I was told at least 20 times that my radio (which was a Kenwood) might be the cause, and that it was interfering with the engine control unit due to feedback to the GALA signal. I repeatedly explained that only the power, memory, and speakers were connected. They didn't believe me. In a completely careless act, someone used a screwdriver to remove my radio, bending the mounting bracket and scratching the trim in the process. They proudly told me that the problem had been found and that the radio was to blame. I, having just returned from work, was shown the "work" that had been done. First, I was shocked, then I looked at the "found" error and could only shake my head. The nice VW employee (an apprentice) had managed to read the wiring diagram of the radio connector upside down and, in the dead of night, cut the wire for the backlight, but he did it correctly. To make matters worse, the master technician disconnected the radio completely right in front of me. Unfortunately, I had lost the code for it, so now the radio is just sitting in the corner. So, the wiring harness was then replaced.

This measurement was taken after the car was brought to the workshop because it was in emergency mode.

No errors detected.
Reading measurement block: 0.

43 111 0 18 94 191 113 155 133 77
133 103 66 34 119 190 72 156 150 109

Now, at the end of summer 2005, on the way to Denmark, on the A7 highway, it happened again.
While in the left lane, suddenly the car lost power and slowed down during an overtaking maneuver. I was initially startled, but I turned on the hazard lights and pulled over to the emergency lane. After turning the car off and on again, it started working again. I stopped in Kassel and immediately went to a VW workshop to have the error codes read. The result was: "Implausible signal from sensor ½ for accelerator pedal position - G79 + G185." The error codes were cleared, and I continued driving. Two weeks later, back in Germany, I visited the workshop again and reported the problem. I also asked about the possibility of getting a refund. However, they said there was nothing they could do, as I had already received one or two new control units. When asked what to do next, I was told to just drive it for now, as it's unlikely the problem will reappear. Almost as soon as I got home from work, I was driving off the highway and experienced the same issue again: no power and the accelerator wasn't working. I called the workshop and explained the situation. A week later, I was on my way to Oktoberfest when it happened again, right in the middle of the A9 highway. Stuck in traffic, the engine speed dropped to 1200 RPM. I tried the "restart" trick again, but it didn't work. The error persisted after starting the engine. So, I drove it to the next exit. I parked on the side of the road and tried again, but without success. I then turned off the car for the first time and called for help. 15 minutes. Later, the car started working normally again. I took it to the workshop and, luckily, I managed to catch the boss there on Sunday evening. Connected to the large diagnostic device, and 2 errors were detected:

17664 P1256 035
Coolant temperature sensor. G62
Interruption/Short circuit after the positive terminal.
intermittent error
sporadic error
occasional error

18047 P1639 035
Accelerator pedal position sensor: G79 + G185.
implausible signal

Occasionally, I've noticed that the engine's idle speed fluctuates, and sometimes on the highway, there are brief, small drops in power, between 2000-3000 RPM, while driving at a constant speed, but only for a short time.

So, here I am, having been promised that my car would be repaired. I've been waiting for a call for two weeks now. I'm about to go to a lawyer and explain the situation to him, and demand a refund. And selling the car.

If anyone has a suggestion or a piece of advice, I would be grateful.
Best regards,
K@pu

Hi,
Have you ever looked at the wiring diagram to see how the power supply is implemented from the engine control unit?

Best regards, Rainer.

Here are the pictures of the "new" wiring harness. *SHOCK*

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Bitte nutze 'Attachment hinzufügen' bzw. das Upload Forum hier.

I read that corroded contacts can be a cause of errors.
Unfortunately, I don't yet know where the wiring harness from the pedal connects to the control unit, and where one can check it.

But I have a long list of things the workshop can check, and potential solutions, without having to replace the control unit right away.
Best regards.

/PS: The LMM (likely referring to a mass airflow meter) was replaced free of charge in the summer of '92.

@Rainer K.
"To do that, I first need to understand the circuit diagram in more detail." I got myself the:
1.9L turbocharged diesel engine / 85kW, engine code AJM.
"Viewed the circuit diagram starting in August 1998." Although I'm an electrician, I'm not familiar with this type of plans.

Well, there you have it – the cause of your problem. The tangled wires were probably caused by the same type of person, 'Leerling', who also disconnected your radio... The only solution is probably to replace it with a new wiring harness – this time, one that's pre-wired with connectors.

Hi,

@K@pu,
I had a similar problem some time ago. The car went into limp mode with an increased idle speed.
'The memory error was also related to the accelerator pedal sensor, but the cause was oxidized contacts on the MSG (Modular Service Gateway).'
and in the connector of the MSG. Among other things, the orange seal in the connector was torn.
I then replaced the seals on both connectors and cleaned the contacts.

Achim wrote:

Hi, @K@pu, I had a similar problem some time ago. The car went into limp mode with an increased idle speed. "The memory error was also related to the accelerator pedal sensor, but the cause was oxidized contacts on the MSG (Modular Service Gateway)." and in the connector of the MSG. Among other things, the orange seal in the connector was torn. Then I replaced the seals on both connectors and cleaned the contacts.

Here's a translation of the German text:

"A question from someone who always wants to learn something new: what is msg?"

I have an appointment with the lawyer tomorrow.
2: Should I tell my VW workshop anything else? (I've read through the forum, and in none of the cases was the control unit replaced.)

Thank you again for your responses.

Hello K@pu,

That's a very sad story.
I am very confident, like my predecessors, that the problem lies in the connector between the engine wiring harness and the engine control unit (ECU).
A verschandeln solution would be to completely replace the entire engine wiring harness, including the connectors. I would absolutely not tolerate this aftermarket wiring, as shown in your pictures; it's outrageous. I would also have the interior wiring harness completely renewed; it's completely unacceptable to just cut and splice wires (what's the point of workshops having unlocking tools if they don't use them?). While the workshop will likely resist with all its might, because it involves a huge amount of work and often causes more damage than it fixes, you should definitely apply pressure.
If the car catches fire due to a cable malfunction, the partial casco insurance will not cover a single penny of the damage.
The reason for the failure, as I've also experienced, is always related to moisture. To quickly resolve the issue, we would completely wrap the entire wiring harness, including the connectors and the engine control unit, in plastic film after drying, and then seal it. This provided improvement, but it's not a permanent solution.

Hi again,

I once told this story to a new colleague.
His father has a workshop in the north.
Okay, his father is aware of the problem, but the cause of the error was:

As I understand it, the timing gear on the crankshaft had some play, maybe around a millimeter or so. However, that was enough to trigger the same error that caused the car to go into limp mode.

Okay, if I and he have understood correctly, then that's also a possible solution to the problem.

Best regards.

We were just experiencing the same error with the newer model.
The problem was a widened connection pin (someone had apparently drilled directly into the terminal to take a measurement).

First, the throttle pedal sensor was replaced. Then, all 6 pins on the engine control unit (ECU) were replaced, but the error reappeared. Finally, all the pins on the sensor itself were replaced.
The error is still there. Then the engine control unit error is still there!
Then came the long faces and a VERY long debugging process.

Deep within the cable harness, there was still a connector. It contained a PIN, a slightly bent (I'll call it a female) connector, but that was it. Since then, the error has never reappeared.

Hi, I've been following your problem closely. Did you also check the 109 relay during your troubleshooting? I had a similar issue with my Sharan once, and it turned out to be the 109 voltage relay, which had a faulty solder joint. Replacing the relay fixed the problem.

Sure, here's the translation:

'Hello.'

Quote:

the engine was running at 1200 RPM

That probably won't be the case anymore with relay 109, though...

pschaefer wrote:

Quote: The engine was running at 1200 RPM . That shouldn't be the case anymore with relay 109...

The engine never actually turned off; it always just went into a fault state, with the preheating indicator flashing at the same time.

The last time, even turning it off didn't help; it only stopped for 15 minutes, and then it started again .
Best regards.

Okay, after so much time and several visits to the workshop, they are at a loss.

The engine would also repeatedly start with different idle speeds, ranging from 800 to 1200 RPM.
Okay, here's the translation:

"And now for the crucial part: I opened everything up and, with the engine running (when the idle speed was once again above 800), I checked the wiring in this homemade wiring harness. That's when it happened --> the idle speed fluctuated. The amazing thing was --> the connection between the potentiometer and the wiring harness."
After so many repairs, everything has been replaced, but the corroded connector was left in place, and even a new wiring harness was installed.

I added some injector cleaner or something like that, and now the idle speed is okay. The problems have disappeared for the past two days, and there are no more error messages or limp-home modes.

Okay, I'm going to the lawyer now.

Best regards.

Hello! I'm new here and I'm from Austria, so please, as a newbie, I'm asking for your help! I have a VW PASSAT 3B HIGHLINE ESTATE with 115 HP (85 kW), manufactured in 2000. I've been having a problem for the past six months with the error code for the accelerator pedal position sensor (G79) and the throttle valve control module (G185): "implausible signal."
I've been to more than 6 workshops, and various parts have been replaced, but the problem is still there! I've been towed by the ÖAMTC (Austrian Automobile Club) 4 times, and I've already spent far too much money on it! The gas pedal sensor has been replaced twice, and some cables as well. The error code has been cleared several times without success! Is there no mechanic or electrician who can fix this problem? What could be the cause? I'm about to lose it! I've almost lost my job because I haven't been on time for work! I'd like to take it on myself, but I'm inexperienced with these things. Is it possible to repair it somehow? Is it even repairable?r So, I'm already starting to despair. I can't sell my beloved Passat, not in this condition anyway! I have a girlfriend who lives 800 km away, and I'm going to marry her soon! And I have to drive to her every weekend, otherwise I won't be okay! I love her so much and I need to solve this problem as quickly as possible! Please help me!! I would be very grateful to you! With kind regards! Lukas[/b]

'We also experienced this issue. The most permanent solution is to completely replace all the wiring from the accelerator pedal to the engine control unit (ECU).'
We initially tried replacing individual pins here and there, but it didn't solve the problem. Eventually, we replaced all the wiring from top to bottom, and we've never had any issues since.