Passat 3C Glitches

Hello!

After the supposedly defective ZMS (where a new one is already waiting to be installed), there's another problem, which, in my opinion, has nothing to do with the ZMS issue.


Vehicle: Passat 3C, 212,000 km, manufactured in 2008, 140 HP TDI, Common Rail.


Error description:

- Short-term interruptions in the partial load range, especially after load changes.

- It feels like the interruptions last for about 1 second. During this time, it feels like the engine has no power.


- Gas is always accepted immediately.

- No errors in the error memory!

Assumption - previous troubleshooting steps:

- Based on internet research, the problem may be related to the fuel system. -> The diesel filter was replaced approximately 20,000 km ago. Visual inspection revealed no leaks.

- Furthermore, faulty temperature sensors are suspected to be the cause. I just took a test drive and logged all the temperature values (data blocks). The error occurred three times, but there were no unusual readings in the temperature data.

I don't know what to do next. I assume that the error can only be detected by logging the measured values.
My question is: Which measurement values are relevant, and how should they be interpreted?

Thank you!

Manuel.

Without addressing the errors, this discussion doesn't make much sense.

There are so many possibilities.

Or should we consult the crystal ball?

Please perform an auto scan.

Hello everyone!

I had some free time last night and performed an automated scan.
Just before the scan, another problem arose: the ABS warning light and the brake system warning light illuminated while the vehicle was in motion.

Now, regarding the scan results:

01316 - Brake control unit, intermittent fault.
00285 - Front right speed sensor (G45), intermittent short circuit to ground.
01810 - Temperature flap servo motor, right side.

My initial conclusion:

The wheel speed sensor on the front wheel is triggering the ASR (Anti-Slip Regulation) system - due to the intermittent error, this results in a brief reduction in engine power in certain situations. Is this a plausible explanation?

I'm not sure what's going on with the brake control unit, but it's possible that there's a connection to the speed sensor as well.


Regards,
Manuel.

Please upload the Autoscan.

Hello Rainer,

Attached is the car scan.

LG
Manuel.

Hello Manuel,

Has the EGR valve been replaced in this engine before? Take a look at whether there are significant discrepancies between the actual and desired air mass values when driving under partial load (full load disables the EGR system).

How frequently do these glitches occur? Can they be retrospectively linked to specific locations or timestamps in a log, or are they rare events?

Are the transitions from disruptive behavior to normal behavior more abrupt or more gradual?

Best regards, Rainer.

Hello!

The AGR was replaced about 3 years ago. I will review or log the target and actual values for air mass this weekend.

The spikes are steep and, as mentioned, very short. These [phenomena] can occur once per kilometer, or even only once every 5 kilometers, but this is just a guideline for frequency. It seems there is a higher frequency when driving on curves.

I was just driving the car a little while ago, and I noticed that, similar to the engine cutouts, the ABS system activates (for a very short time) when I lightly brake on a smooth, non-cracked asphalt road.

The warning lights for the parking brake, ABS, and ASR are constantly illuminated in yellow.

Today, I'm going to try to locate the fault with the front wheel speed sensor.
Next week, it will be lifted onto a platform for the replacement of the dual-mass flywheel (ZMS). I hope that by then I will have also verified the other errors.

Regards,
Manuel.

Quote:

Outages are steep and, as mentioned, only very short. These [phenomena] can occur once per kilometer, or even only once every 5 kilometers, but this is just a guideline for frequency. It seems there is a higher frequency when driving on curves. I was just driving the car a little while ago, and I noticed that, similar to the engine cutouts, the ABS system engages (for a very short time) when I lightly brake on a smooth, non-cracked asphalt surface. The warning lights for the parking brake, ABS, and ASR are permanently illuminated in yellow.

The ABS/ESP system can also reduce engine power, so it's important to check that the acceleration and speed sensors are working correctly, providing accurate values, and that all wheel speeds are displayed consistently.

Therefore, you should replace the crankshaft sensor located at the front right (using a diagnostic scan tool) and check the wiring before continuing your search.

Best regards, Rainer.

Hello!

Yesterday, I took a closer look at the wheel speed sensor and noticed that the cable was frayed in one spot.
Firstly, there was an intermittent break in a wire, and secondly, there was also a short circuit to ground.
The error has been temporarily fixed (a new cable has already been ordered), and sure enough, all the warning lights (parking brake, ABS, and ASR) now turn off correctly after the engine starts.
The engine cut-outs (caused by the ASR) are gone.


Regards,
Manuel.

Thank you for the feedback .