2000 A4 TQM (ATW), 144k on it.
A few months back CEL came on, I scanned it and it was the after-cat O2 sensor.
I replaced it with a brand new one, that is 5k miles ago.
Cleared the faults, CEL came back almost immediately, another code this time.
Today I replaced the front O2 sensor, brand-spankin' new, both purchased from AutoHausAZ.
Here's a photo of the old and new front O2 sensors (crappy iPhone one):
Drove the car for about 10 miles, CEL is back on:
Control Module Part Number: 4B0 906 018 P
Component and/or Version: 1.8L R4/5VT G 0008
Software Coding: 07201
Work Shop Code: WSC 06335
1 Faults Found:
16518 - Oxygen (Lambda) Sensor B1 S1: No Activity
P0134 - 35-00 - -
I searched all archived threads here (B5 forum) and the 1.8T forum as well.
Someone suggested checking the fuses - all are good and dandy.
Another thread mentioned replacing the vacuum lines - all of them
I already replaced with new rubber.
The car has no problems at all (knock on wood), gets fine gas mileage.
Had it checked at a local muffler, there are no exhaust leaks.
What gives? Is it the cat is kaput or downpipe or what the fück?
I am baffled. Any ideas or tips are appreciated