Check Engine Light (On and Off)

Brian Pleet bpleet at
Sun Oct 31 01:49:07 EDT 2004

Thanks for your responses. I thought you'd like to know the outcome.

The issue was the replacement O2 sensor. A call to Shokan got me their 
version of the generic, but Bosch sensor for the S6. Once replaced, the 
check engine light came on once more for 20 seconds and not once since.

Lesson learnt....get the right parts, first time.


My 1995 S6 has been relatively problem, free right up to right now @ 135k km.

A month ago I participated at an Audi Club track event in Edmonton Alberta. 
The car performed beautifully and I had a ball. On the drive home (10 
minutes from the track) the check engine light came on and has been going 
on and off for 4 weeks.

The dealer said the soft code included "poor fuel mileage", and "driving at 
high RPM"....very insightful. They reset the codes and sent me home. On the 
way home the light went back on again.

My local mechanic found more issues, including "fuel pressure out of spec" 
apparently in the same soft code. He replaced the fuel regulator because 
the pressure was not correct. The light is still going on and off. 
Sometimes, as if I started the car differently, the light stays off until I 
accelerate, then comes on for a few seconds. Other starts leave the check 
light on from the time I turn the key and occasionally the light will go 
off when I release the accelerator.

Three months ago I had to replace the EKT sensor because on occasion (never 
a good time) the car would not start. At the same time, my mechanic 
replaced the O2 sensor, which was original, but used a generic sensor with 
two leads instead of three.

Curious, (and frustrating) but is there a pattern that no-one has yet 

Suggestions appreciated.

Brian Pleet
95.5 S6 Europa Blue
Calgary, Alberta  

More information about the quattro mailing list