Audi A2 8Z AUA Engine Lambda Sensor

Hi.

My son's friend's A2 is having problems with the oxygen sensor. The check engine light is on, the error code cannot be cleared, and it reappears immediately after being cleared and the engine is started.

I swapped the sensors from one car that was accessible this morning. The other car runs perfectly with these sensors, and conversely, the sensor from the donor car produces the same error code.

I checked the wiring harness in the engine compartment as much as possible, and everything seems to be in order.

Perhaps someone has suggestions for the next steps.

In the car scan, all error codes are clearly displayed.

Thank you.

Hello Ruedi,

Take a look at the anomaly detection. If you experience occasional, sporadic misfires, this message may appear.
The error should then be able to be deleted.

Otherwise, there is a software update for the engine control unit related to various issues. Errors related to mixture formation.

What software version is installed on the engine control unit?

How does the fault manifest itself? (Aside from the illuminated check engine light,) is the engine running unevenly, is it misfiring?


Best regards,

Michael.

Hello fellow namesake.

There are no misfires, the engine runs smoothly, and there's no jerking or shaking while driving.

I can clear the error code, but a few seconds after the engine starts, the error reappears immediately.

If I look at the measurement blocks, I can see that the sensor is working, and it immediately stops when the check engine light comes on.

Due to a software update, I read in the A2 Friends forum that the one installed here cannot be updated...

Maybe someone else knows something new.

Thank you.

Rüdi wrote:

I checked the wiring harness in the engine compartment as much as possible, and everything seems to be in order.

What distance were you able to measure? Until the MSG?

Could there possibly be a defect in the MSG?

Is the error pattern the same when disconnecting the wiring for the oxygen sensor?

Okay, I started by taking measurements in the engine compartment, identified some wires, and I've managed to get a wiring diagram. When the car is back here, I'll measure the voltage from the oxygen sensor to the engine control unit (ECU).

I also did some research online, and it could be that the MSG (Modular Signal Generator) is no longer able to interpret the data from the sensor, even though it worked fine in another vehicle. This is usually fixed by modifying the software, but there's no way to do that for this particular MSG.

However, it's possible that the car has only been used for short trips in city traffic over the past two years.

Rüdi wrote:

I also did some research online, and it could be that the MSG (Modular Signal Generator) is no longer able to interpret the data from the sensor, even though it worked fine in another vehicle. This is usually fixed by modifying the software, but there's no way to do that for this particular MSG.

"How do you know that there is no update available for this specific module? Did you get that information from Audi?" If there's no software update available, is there perhaps a specific oxygen sensor that is compatible with the MSG?