2011 Q7 TDI - Engine Light
 

Hey everyone,

Here is the problem I am experiencing.

The engine light has been coming on in the car since October. Since I live in cold climate, my heater is always on. I have noticed whenever the car is idle for over 5 minutes with the heater on full, the engine light comes on.

I took it to the dealership 3 times already. The first time, they reset the light. The second time they did a thorough diagnostic and found nothing wrong. The third time, they diagnosed it and found the knock (or NOX or NOK) sensor to be the cause, they replaced the sensor did a 300km road test and found nothing wrong. A few days later after I drove it around...the engine light came on AGAIN.

What do you guys think? Any suggestions?

I think its the problem with the sensor wiring. The dealers would not have checked the wiring did they.

Is there a leak or damage on the exhaust pipe of the Aux heater?
Is there a fail on the sensor programme of the Aux heater?
Does the Aux heater shut off after 5 to 10 mins after startup.

I just wonder if the engine is picking up fumes from shut down of the Aux heater. Mine shuts down with a black puff of exhaust if it purges when shut down occurs during a flame cycle. It is much more obvious if it occurs when the car is stationary. I do not usually leave my car idle that long unless it is frozen... Ireland.

This *seems* to be a common issue, several of us have been hit with this intermittantly. I have had it happen three times. Check out this thread: https://www.audiworld.com/forums/sho...&highlight=NOX

No answers, but yes, it's a known issue.