Knock (NOX) sensor needs replacing
 

Hi Folks!

2010 Q7 TDI - Check Engine Light (CEL) came on and stayed on. Dealer said knock sensor needs to be replaced at $$$. Tech cleared the CEL. Searched our forum, saw a few past incidents, and now need advice on a couple of questions:

1. Can I drive the Q7 until the next CEL or will I cause damage somewhere else in the engine? Will I subsequently hear knocking coming from the engine bay and what does that really mean?

2. Is this an easy fix that an Indy repair center can perform without unknowingly breaking something else?

3. Do you find it worth the dollars spent on an extended warranty like the 2yr/24K miles on a Platinum coverage for $2,600 when I am putting in 14K miles a year?

Checked my 2010 USA Warranty book and no coverage there too -

A. Federal Emissions Control System Defect Warranty for 8 years or 80,000 miles includes major emission control components only:
- catalytic converter
- engine electronic control module
- on-board diagnostic device

B. California Emissions Warranty Supplement covers for 7 years / 70,000 miles on the knock sensor only for the S6 5.2 vehicle.

Thanks in advance!

causes no damage or driveablilty issues….mine went out…fixed under warranty though…"known" issue for TDIs apparently….

Mine came on today, same code. 2011 model first emissions light ever.

it is making me rethink my decision to buy DEF from (non-dealer).
I bought an Audi bottle then cut a hole in bottom and used the DEF from one of the chain stores. Now in less than 600 miles I have this P2201

I have heard there was supposed to be a calibration TSB for this but I can't find it.

I am going to leave this alone. I don't think it needs replacing.

I think I am also.
But I think I found the TSB in another post here on the site TSB#2022479/1
Can anyone confirm if this is valid for 2010 and 2011 models (OP and Mine).

I am going to reset the code and see how it goes.

After resetting the code it stays gone until driving a good many miles!
I put about 200 city miles on it with no light

I left DFW and went to Houston for the weekend - about 350 miles down/around Houston. Then on the way back Monday evening about 200 miles driven the light came on - P2201


fuel cap is tight (they don't click)
'reputable' diesel stations
absolutely no loss in performance/mileage


I found this TSB for NOX on this site but I cannot find anything more on it like a description or anything and my dealer says it is not recognized!! TSB#2022479/1

Does anyone have a website or printout listing this TSB and what it is for and if its valid?

Thanks!

Still driving with no CEL popping up again.

I just had the NOX sensor error on my 2011 Q7. The genius at the dealership said he'd have to check with the technician before allowing me to leave as he didn't know if it would damage the engine to drive it. Looks like a need to find a dealership that believes in customer service over profit.

I do trust my service advisor and the senior tech who always work on my Q7 and S6 (as well as my past S5) and even though it needs replacing, resetting the CEL and doing a wait and see is a much less expensive option ($800).

More links that may (or may not) be useful:

https://www.audiworld.com/forums/q7-...ensor-2832432/

https://www.audiworld.com/forums/q7-.../#post23879227

I used to trust mine. I had great service with them for many years. Unfortunately, the dealership was sold. In the last two years they have replaced all their service advisers. I had the CEL reset and will wait and see if it comes back on.