iversond1

My engine light came on on my 1997 Audi A4 2.8 (not the quattro). I tried to resolve the issue, but I am no mechanic. Basically the issue was with the following: Post-cat sensor (B2 S2). I read the tech article and checked the pins on the sensor side with an ohm reader and it appeared the heat sensor was bad. I don't have a lift so I called on an Audi Specialist. He said he found the o2 sensor bank 2 sensor 2 was defective and needed to be replaced. I would have thought when I popped the hood and looked at the brown connectors near the firewall (sensor side) would appear brand new and the wiring down from the connector would appear new as well. It all is the original. So is it just the sensor itself that is replaced which is down below the engine? It was $200 for the o2 sensor. I don't mind paying slightly higher for the trouble of purchasing the parts, but I'm hoping I didn't pay that for no parts at all. If someone could ease my mind on this, it would be helpful.

MartinH

instead of installing a complete sensor and harness. It can be a pain to thread the wires so this is a normal DIY procedure.

iversond1

Thanks for the explanation. That makes sense. Yeah, I now have an issue with the engine coolant temperature sensor. It looks slightly easier, but still difficult to get through the maze of tubes and wires behind the engine.

JS///w124\\\B5

Im about order an o2 sensor for my 2.8 but just had a quick question. Would B2S2 be driver side or passenger side?

A400

I have found that the replacement O2 sensors work fine if you go to the step of soldering (sp?) the connectors. I solder all wires I replace and since I run an aftermarket ECU this was a lot, but I havent had the 1st connection problem. Seems like overkill I know, but since so many problems on these cars can be hard to trace I feel it is worth the trouble and the more you do the easier it becomes.
Rod

JS///w124\\\B5

....so is b2s2 driver or passenger side

AudiMick

Drivers side rear sensor (post cat).

The only thing that sensor does is monitor cat converter efficiency. Doesn't affect running at all.

MartinH

Driver's side

MartinH

But you need it working to pass Mass inspection

JS///w124\\\B5

Thanks for the help. Ill order it tomorrow.