Audi A3 1.8T HELP!!

[ed400]

Hi guys,

My friend has an Audi A3 1.8T (2003) which has been giving him some grief.

It was misfiring, hunting for idle and freezing the brakes. Plugged my OBD tool into it and it turned up fault codes relating to the lambda probes. I got hold of both probes and promptly replaced. The 2nd probe on top of the cat was showing bare wires (no heat sheild) and, after replacing it, it is still showing error codes.

My question is, has it blown something in the ECU which is now not registering that its there? From looking at the o2 graphs through the OBD it doesnt seem to be doing a lot.

Any help appreciated!

[Robatr0n]

Fault codes can still show up after a fault has been fixed. Basically the ECU needs a chance to reset by either unplugging the battery for awhile or pulling a particular fuse out of the fuse box for a few minutes.

Before you ask, no I dont know what fuse it is!

Out of interest, how has his car been behaving since you changed both sensors?

I hope there is nothing seriously wrong with his car.

[ed400]

Must admit I didnt think of resetting the ecu! I'll give it a go!

[ed400]

Robatr0n said:

Out of interest, how has his car been behaving since you changed both sensors?

I hope there is nothing seriously wrong with his car.

The car runs perfectly now, just persistanly coding...I'm hoping theres nothing big on the horizon either...eek!

[ed400]

Ok, spoke to soon...the hunting has returned.

Had a look at the car earlier and, even with the o2 sensors unplugged, its still registering variations in amps. Tried an ecu reset but no joy.

Does anyone know if the lambda probes talk straight to the ecu or whether they have their own control unit?

[ed400]

Quick update, Mr RAC man has visited and diagnosed the hunting problem down to a faulty one way valve between the inlet manifold and the master cylinder...just the lambda issue to sort.