Audi A4 TFSI: Starting Issues & Power Loss Fixed

Having worked on my Audi A3 2.0 TFSI (2006) with similar symptoms, I can share my experience with moderate automotive expertise. The symptoms match what I encountered, engine misfires, difficult starts, and power loss. Initially thought it was the camshaft position sensor, but my mechanic found a loose connection in the wiring harness leading to the sensor. The check engine light was definitely a key indicator. The repair involved: Testing the camshaft sensor connections, Repairing damaged wiring, Clearing error codes, Test driving to confirm fix Total cost was 95 Euro for diagnostics and repair. The stalling engine issues disappeared completely after fixing the wiring. To better assist, could you share: Any error codes from the check engine light? Does the engine misfire more when cold or warm? Have you noticed any unusual sounds from the timing chain area? When was your last timing service performed? These details would help determine if your issue is identical to what I experienced or if other components need inspection.

My A4 has 119975 KM and had its last major service 6 months ago. Had a complete check of the timing belt. Your wiring suggestion makes sense since the stalling engine symptoms started gradually. Got the error codes checked: P0340 and P0341, both pointing to camshaft sensor failure. The misfires happen mostly when the engine is cold. No unusual sounds from the timing chain area. What I have noticed is the check engine light flickers occasionally before staying on permanently, which might support your theory about loose connections causing timing issues. Did your automotive sensor show similar intermittent behavior before the final fix? Or did you experience a sudden complete failure?

Thanks for the additional details about your A4. Those error codes P0340 and P0341 are exactly what my A3 displayed before the repair. The flickering check engine light was also identical to my experience, definitely a classic sign of camshaft position sensor connection problems. The intermittent behavior you described matches my case perfectly. My sensor issues started with occasional misfires during cold starts, then progressed to more frequent timing issues. The flickering engine light appeared about 2 weeks before the sensor failure became more severe. A few key points from my experience: Cold start problems got worse over 3-4 weeks, Engine power dropped gradually, The intermittent sensor readings caused timing issues that worsened with time, Repair cost was minimal since it was just wiring Based on your timing belt service being recent, and the matching error codes, this really sounds like the same electrical connection problem I faced. The camshaft sensor itself might be fine, just receiving poor electrical contact. Worth checking the wiring before replacing the entire sensor unit. Would recommend having the wiring harness inspected, particularly the connection points. Are you noticing any correlation between weather conditions and the symptoms?

Based on your detailed explanation, I believe we are dealing with the same issue. The weather actually seems to make a difference, the rough idling and starting problems are noticeably worse during damp mornings. This further supports the wiring connection theory rather than a complete sensor failure. I will have my mechanic check the wiring harness first, focusing on the connection points you mentioned. The gradual progression of symptoms matches exactly what you described, it started with occasional cold start issues and has slowly gotten worse over the past month. The timing issues are concerning, but knowing your repair was successful without major component replacement is reassuring. Since my recent timing belt service showed no problems, and there are no unusual sounds from the crankshaft area, I feel more confident this can be resolved with wiring repairs. Will book an appointment to have the electrical connections checked and report back with the results. Thanks for sharing your experience, it saved me from unnecessarily replacing the entire camshaft sensor unit.