A4 Camshaft Sensor Failure Causes Random Stalling

The symptoms you describe match what happened with my 2017 A5 last winter. The stalling at idle and starting problems were identical, and sensor testing confirmed a faulty camshaft position sensor combined with a worn encoder wheel. The camshaft sensor works with the crankshaft sensor to manage engine timing. When either fails, the engine control unit gets confused about valve timing, leading to those exact symptoms, rough idle, stalling, and check engine light activation. The repair involved replacing both the camshaft sensor and the encoder wheel mounted on the camshaft. This was a serious issue requiring proper diagnostic equipment to verify, as similar symptoms can come from other timing-related problems. My vehicle needed about 6 hours of labor since accessing the camshaft position sensor required removing several components. The check engine light cleared immediately after repair and the stalling never returned. Given your low mileage, this could be covered under warranty. Have it properly diagnosed with a scanner that can read detailed sensor data rather than just basic fault codes.

Thanks for sharing your experience. Almost the same happened to my 2019 A4 a few months back when the camshaft sensor failed. The ignition timing was off and caused similar stalling issues. Really good point about the encoder wheel, would be smart to replace both at once. Did you remember roughly what repair cost you had to deal with? And has everything been running smoothly since the fix? My engine has been perfect after the sensor replacement but curious if you experienced any related issues pop up later.

Thanks for checking back. Since having the camshaft sensor and encoder wheel replaced, my A4 has been running flawlessly with no engine misfires or check engine light issues. The repair cost me 695 Euro total, which covered both parts and labor. The engine control unit readings have all been normal, and the ignition timing is now perfectly synchronized. Looking back, fixing both components at once was definitely the right call. The mechanic explained that a worn encoder wheel can damage a new sensor if not replaced together. The improved engine performance and smooth idle confirmed this was the root cause of the stalling problems. Going on 8 months now post-repair without any related issues popping up. The crankshaft sensor readings are stable, and the engine runs like new. Glad to hear your repair worked out similarly, these sensor issues can be tricky to diagnose but usually resolve completely once properly fixed.

After dealing with the stalling issues, I finally got my A4 fixed last week. The repair shop confirmed it was indeed the camshaft position sensor causing the problems. They ran complete sensor testing which showed irregular timing signals. The mechanic found both the camshaft sensor and encoder wheel were worn. Total bill came to 780 Euro including parts and labor. The check engine light cleared right after the repair, and the engine now starts perfectly every time. The interesting part was discovering the crankshaft sensor was also showing early signs of wear, though still functional. I decided to have it replaced while they were already working on the timing system. Better safe than sorry. One week later and the car runs better than ever, no more stalling, smooth idle, and perfect cold starts. Really glad I didn't wait longer to get it fixed, as the mechanic mentioned prolonged sensor issues could have led to more serious engine problems.