I have some kind of issue with a 2001 Audi A4 1.8t. I recently replaced all the coils because 1 was bad. This made the car drivable, but I am still getting the following codes. I tried driving very fast for a while in case the sensors were carboned up, but it did not help. I have attached some screen shots of some logs. Does it seem like the Pre-cat o2 sensor is bad?





Thursday, 06 January 2011, 19:19:33
VAG-COM Version: Release 409.1-US

Control Module Part Number: 4B0 906 018 M
Component and/or Version: 1.8L R4/5VT G 0003
Software Coding: 16251
Work Shop Code: WSC 40907
4 Faults Found:

17584 - Bank1: O2S (Lambda) Correction Behind Catalyst: Control Limit Reached
P1176 - 35-00 - -

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -

16685 - Cylinder 1 Misfire Detected
P0301 - 35-00 - -

16686 - Cylinder 2 Misfire Detected
P0302 - 35-00 - -

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Yes, it looks like the pre-cat sensor is bad. B1 S1 is pre-cat. B1 S2 is the post-cat sensor. They're usually under $150 online. Just make sure you check your engine code and get the correct one.