Accelerator pedal defective, according to diagnosis

Hey everyone,

My Passat is currently having quite a few problems, maybe someone here knows a solution.

The car has broken down on me three times now, twice due to hitting a bump on the highway at around 170 km/h.

While idling, the engine was running at 1100 RPM, with no response to the accelerator pedal. The display showed "Engine malfunction, workshop!" and the ESP light was illuminated. After a restart, it initially seemed okay, but immediately went into the aforementioned "limp mode" when the accelerator pedal was lightly touched.

The diagnostic system consistently reports an intermittent "Throttle Position Sensor" error (I don't know the exact designation – it refers to the accelerator pedal), indicating an implausible signal – intermittently. Both sensors in the accelerator pedal were identified as faulty.

The accelerator pedal has now been replaced, but the problem still persists.

Do you have any idea under what other circumstances this error might occur?
During the inspection, I mentioned it, and at that point, the service advisor said he had a case where biodiesel was responsible for this type of issue (I find it hard to believe, but it might not be impossible).

Möchte vermeiden das die Jungs von VW nun in den Teiletauschrausch kommen.

Sure, no problem. Here's the translation:

"Thank you in advance and best regards,"
Benni.

A loose connection in the plugs or a broken cable... In those cases, simply swapping the pedal won't help much.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Well, biodiesel and the accelerator pedal definitely don't seem to go together at first glance.
Do you have a VAG-COM diagnostic tool available? Could you check if the accelerator pedal is sending the correct values?
In your case, without knowing the exact problem, I believe a contact issue or a faulty/worn connection from the pedal to the MSG is very likely.

I don't have a VAG-COM device available right now. When the ADAC (German Automobile Club) and the car dealership checked the sensor, everything was fine.

I also suspect it might be a cable issue, and I hope it doesn't mean replacing the entire wiring harness.

Dieser wurde schon mal bei einem Amaturenbrettaus und einbau eingeklemmt (hat meine Werkstatt mit Fotos dokumentiert). Schuld war ein anderer VAG Händler lt. Repair history.

Apparently, only the wiring was wrapped around the cable harness, but it's certainly possible that there could be consequential damage as well.

I also noticed a gurgling or hissing sound coming from the windshield washer system, seemingly originating near the MSG (presumably a module or component). I hadn't noticed this before (before replacing the windshield and installing a heated windshield), so there might be some shoddy workmanship involved.

*sigh* Okay, I'll inform the dealer. Right now, it's at a rather small dealership, and I hope they still have some "common sense" when it comes to trading, instead of just trying to swap everything around randomly.

Thank you all very much.
My primary concern was whether such an error could also trigger other abstract errors – for example, biodiesel.

Windshield replacement?

For example, the cover of the water collection basin might be torn, which could have flooded the entire area. Take a look inside the water collection basin; there might be a small pond formed inside.

Hello,

I once had the same problem: increased idle speed and no response.
Accelerator pedal position. The problem was caused by moisture in the MSG (presumably a control module) and oxidized contacts in the connector.

Does anyone happen to know if the accelerator pedal is directly connected to the engine control unit (ECU), or does it go through the comfort control module first?

The reason I'm asking is because there's about 3 centimeters of water standing beneath the insulation, and there are several wiring harnesses floating in it, including the control unit housing.

Okay, so it seems we've found the cause. There's a leak in approximately a 15 cm wide area of the lower windshield adhesive, directly behind the instrument cluster. When water runs over the windshield, it sounds like gurgling from a bathtub drain inside the car, and a lot of water is getting behind the pedals and under the insulation.

Today, we are going to take everything out to dry the car again.

Hi,

The accelerator pedal is directly connected to the engine control unit (ECU).

Good luck with the drying process; changing the green bin and old newspapers every few days can help somewhat.

Best regards, Rainer.

Thanks, I think and hope that the humidity might have been responsible for the error.

To allow it to dry, the car will spend a few nights in a warm paint booth; not too hot, but I think it should dry fairly quickly.

Otherwise, we have now lifted the carpet and insulation, and managed to extract quite a few liters of water.

Well, starting tomorrow, we're going on vacation to Denmark for a week in a different car. It needs some time to dry out, and hopefully it will be working again after that.

My condolences for your bad luck!

The increased idle speed described here is actually normal if the driver demand sensor fails. This is intended to allow the vehicle to be driven, albeit in a limited way, to the nearest workshop.
This function is automatically activated as soon as the accelerator pedal signal completely disappears.

Best regards, Alex.