2011 Q7 TDI - Engine Light
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?