Offset always at -25.5

Hello everyone,

I know this topic is old, but I have a related problem.

I had problems with the DPF (Diesel Particulate Filter) in my 1.9 TDI.

Since the exhaust system had to be replaced anyway, I also had the DPF cleaned. After that, it was reinstalled, and the ash content was reset to 0 using VCDS.

After a few kilometers, the engine check light came on, and VCDS showed several errors related to the differential pressure sensor. So, I replaced the sensor as well and re-initialized it using VCDS. However, something seems not to have worked correctly during the process.
The sensor shows values between -5 and -10 when the engine is off, with an offset of -25.5.

"Also, the error is appearing again:"

Code:

001137 - Drucksensor 1 für Abgas (G450) P0471 - 000 - unplausibles Signal Umgebungsbedingungen: Fehlerstatus: 01110000 Fehlerpriorität: 2 Fehlerhäufigkeit: 1 Verlernzähler: 255 Kilometerstand: 286259 km Zeitangabe: 0 Datum: 2000.00.00 Zeit: 15:38:52 Umgebungsbedingungen: Drehzahl: 798 /min Geschwindigkeit: 0.0 km/h (keine Einheit): -5.10 (keine Einheit): -25.50 keine Einheit): 36.0 Temperatur: 270.0°C Temperatur: 15.3°C

It looks like the offset is incorrect.
I have tried to re-calibrate the sensor several times, but nothing changes. The offset is always at -25.5.

I also tried the pairing process with the ignition on for 5 seconds and off for 40 seconds (repeated 5 times), but there was no difference.

Do you have any other ideas?

If the offset cannot be adjusted to at least a single-digit value via OBD, then the sensor is broken.

Thank you, dieselschrauber.
"But I suspect you're wrong here; the sensor is almost new, and furthermore, I looked at the readings. To do this, I accelerated from idle speed to 4000 RPM with full throttle. The measured value of the differential pressure (MW67/3) increases from -2.55 to 85. See also the attached diagram."

You yourself are writing that the readings when the engine is off are incorrect. What do you think the reason for this might be?

A sensor defect is the most common cause. Could you please clarify what you think answers your question?

I think the offset is incorrect. The offset in measurement 67/4 is -25.5, and the reading when the engine is off is -2.55. I thought the sum should be 0 when the engine is off. Unfortunately, I can't set the offset, and recalibration doesn't seem to be working.

"Dieselschrauber", have you seen the progress? It looks pretty good so far.
I've also attached the complete data here. It's in CSV format and a bit more readable.

Do you really think the sensor is defective? This would be the second sensor to fail within 6 months.

Today I read the error memory again, and guess what:

Quote:

Two error codes found: 001137 - Exhaust gas pressure sensor 1 (G450). P0471 - 000 - Implausible signal. Environmental conditions: Error status: 01100000 Error priority: 2 Error frequency: 1. Lost Count: 255 Time: 0. Environmental conditions: Speed: 0 RPM. Speed: 0.0 km/h (no unit): 0.00 (no unit): -25.50 (no unit): 0.0 Temperature: 168.0°C Temperature: 17.1°C 001138 - Exhaust gas pressure sensor 1 (G450). P0472 - 000 - Short circuit to ground - Intermittent. Environmental conditions: Error status: 00100000 Error priority: 2 Error frequency: 12 Lost Count: 255 Time: 0. Environmental conditions: Speed: 1008 RPM Speed: 0.0 km/h Last: 0.0% Voltage: 11.17 V Mileage: 30 km Temperature: 6.0°C Pressure: 948.6 mbar

Perhaps there is a problem with the wiring (maybe caused by a weasel or something).

Can the cable be replaced all the way to the control unit?
Does anyone know which pins on the control unit lead to the sensor?
Thank you.

Brief reply.

The sensor was working correctly, and replacing the cables (the first 50 cm) near the sensor resolved the issue. After that, it needed to be re-paired, and since then, it has been functioning properly for 2000 km.

Unfortunately, I still don't know about the PINs for the engine control unit.