agentsmith988

<center><img src="http://pictureposter.audiworld.com/111691/ex1.jpg"></center><p>Can someone point out for me where I'm going to find the B2 S2 sensor on my 97 A4 2.8Q? I'm getting the code

Controller: 8D0 906 266 B
Component: 2,8l V6/2V MPI OBD2 D03
Coding: 01201
Shop #: WSC 09218
1 Fault Found:
16545 - Oxygen (Lambda) Sensor B2 S2: Heating Circuit Malfunction
P0161 - 92-00 - Unknown Error Elaboration

So I'm guessing it needs to be replaced. Here are some pictures you can all use to help

DAP@EPL

B2 S2 is the rear driver side O2 sensor.

agentsmith988

any ideas on the difficulty level of the replacement? also, im thinking of getting a used one off a junked audi for 35 bucks. i figure, heck why not?

Shard7

The heater circuit seems to be the weak link for the two secondary sensors, and a used one will probably fail the same way sooner or later.

The sensor is screwed into the top of the pipe, downstream from the cats.

It's a PITA to replace because a) you gotta apply quite a bit of torque to an awkward spot under the car and b) routing the wire back up to the connector on the firewall is tricky and needs to stay clear the exhaust. Without a lift this job will involve a few expletives.

agentsmith988

you have to redo the wiring? why can't you just splice in the new one where the old one was?

AudiMick

How many miles? The cats fail on the 12 valve around 120K, you will have a death rattle.

agentsmith988

What do the cats have to do with the o2 sensor? could it be clogging up the sensor causing it to die prematurely?
and explain the death rattle, since i bought the car it has had a strange sound when the throttle was on, kind of a ticking/rattling sound (thought it was just a loose exhaust piece)

Shard7

the splice would be hanging out under the car and exposed to water, salt, and the heat of your exhaust. Not sure how well that would hold up. There's a good reason why Audi located the connector far away from there.