SQ8 TDI Cold Start Issues: Camshaft Sensor Alert

Similar symptoms occurred on my 2017 Q7 TDI. With some experience working on Audi engines, I can share that camshaft-related issues often trigger the check engine light and cause stalling problems. The engine control unit was reporting irregular camshaft position readings, causing ignition timing issues. After diagnostic testing, the workshop found the encoder wheel on the camshafts was defective, which made the crankshaft sensor receive incorrect signals. The repair took about 4 hours and cost 695 Euro including parts and labor. The workshop also inspected related components to ensure no secondary damage occurred. The stalling problems disappeared completely after the repair. For a more accurate comparison with your situation, could you share: Current mileage, Whether stalling occurs only during cold starts or also when warm, Any unusual engine sounds, When the check engine light first appeared, If you have access to diagnostic codes These details would help determine if your issue matches what I experienced with the encoder wheel failure. Remember that while symptoms might be similar, proper diagnostic testing is crucial before replacing parts.

Thanks for your input. My SQ8 has 193440 KM and had its last service 3 months ago. The stalling occurs not just during cold starts but also when the engine is warm. The dealership performed initial sensor testing but couldn't pinpoint whether the engine misfire was related to the camshaft sensor or crankshaft sensor issues. I checked and got error code P0340 which confirms the camshaft position sensor malfunction. No unusual sounds noticed, but the check engine light appeared last week and has been steady since. Hearing your similar experience gives me confidence to proceed with the repair, though 695 Euro seems a bit steep compared to quotes I received.

I had the exact same error code P0340 on my SQ8 TDI last year. Your engine symptoms mirror what I experienced, particularly the stalling issues when warm. After the camshaft position sensor testing showed irregularities, I went ahead with the repair. The engine control module was interpreting faulty signals, affecting ignition timing and causing those frustrating stalls. In my case, the repair price varied because they found the wiring harness to the sensor was also damaged, requiring additional work. If you're getting lower quotes, ensure they include: Complete sensor replacement, Wiring harness inspection, Proper sensor calibration, Post-repair diagnostic testing My total repair ended up around 750 Euro because of the extra wiring work. However, standard sensor replacement should cost less. The key is ensuring proper installation, as incorrect positioning can lead to persistent engine control issues. The high mileage on your vehicle matches when these sensors typically start failing. Once replaced, the car should run smoothly again, eliminating both the cold start problems and warm engine stalling.

Thank you all for the detailed responses. The P0340 error code and camshaft position sensor issue seems to be a common problem at this mileage. I decided to proceed with the repair at my local specialist who quoted 580 Euro for the complete job, including sensor testing and calibration. The mechanic just confirmed they will also check the wiring harness and engine control connections during the repair to prevent any recurring issues with ignition timing. They estimate about 3-4 hours of labor, which seems reasonable given the diagnostic work needed. Will update once the repair is complete, but feeling confident this will resolve both the car stalling and cold start problems. The consistent feedback about camshaft sensor issues causing these exact symptoms at similar mileage has been really helpful in making this decision.