2006 audi A8 base. I had these codes and many more and cat and evap not ready. I replaced the o2 sensor (driver side) and now i still have the codes listed in the subject. It seems the o2 sensor heater is not working as it should. i i also checked the vacuumlines, they seem ok. I read somewhere the o2 sensors are controlled by the fuel pump relay? I checked the relay the number on it is 191 906 383C. I went online to look for a new relay and several sites suggest the relay should be 8E0951253? Does my car have the wrong relay? Any other thoughts/suggestions?

[Explanation of codes ADDED]
P0150=02 Sensor Circuit Malfunction (Bank 2 Sensor 1)
P0155=02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
P2254=02 sensor negative current control circuit/open bank 2 sensor 1

Tnx.

 

what fuel pump relay does your D3 have? it is in the trunk pass. side, above the battery.

 

I would recommend getting a real scan instead of using a code reader.
Otherwise you'll likely just keep throwing parts at it and may not see all of the problems and underlying DTCs.

 

Before I invest $300, how is vagcom gonna help me? Will it give me more detailed and useful information to resolve this issue?

I looked thru the shop manuals and they don't give any more useful info other then what i found on the www. io

tnx,
Arthur

 

I bought vagcom from rosstech. I'll post details of the scan once I have received the cable.

 

You probably have a fault in the heated oxygen sensor circuit (not the sensor itself). Check the fuse first, and please don't ask which one or where it is because,,,,,,,,,I don't remember.

It is possible also that the bank 1 sensor heater isn't working either but on these cars you may only get a DTC for one side. Something with the way it's wired and the programming in the ECM. If it "sees" a fault in the heater circuit it'll set a code for only one of them. Since the circuit is basically both sides in one, the ECM has no way to really know WHICH heater is out, only that one of them is because the circuit resistance will be out of range.

You should also check the heater resistance of the bank 1 (passenger) sensor right at the sensor itself. Could be a failed pass side will set a drivers side code. Sounds silly I know, but it burned me a couple times on these cars back in my Audi tech days.

Always have to remind everyone a fault code is only a starting point for diagnosis, contrary to what they may tell you at Auto Zone.