Audi A3 Rough Run? Camshaft Sensor May Be Culprit

Having worked on cars as a hobby for several years, I dealt with similar symptoms on my 2008 A4 2.0T. The check engine light and rough running turned out to be a defective encoder wheel on the camshafts, which directly affects the camshaft position sensor readings and engine control systems. After basic sensor testing showed inconsistent readings, my mechanic found the encoder wheel had worn down, causing incorrect camshaft position signals. The total repair came to 695 Euro, including parts and labor. The engine ran perfectly after replacing both the encoder wheel and camshaft sensor as a preventive measure. The repair solved all issues, rough running, hard starts, and stalling. Before suggesting specific fixes, could you share: Current mileage, Any recent repairs, Whether you have access to an OBD scanner for error codes, If the issues happen more when the engine is cold or warm This would help determine if your symptoms match what I experienced with the camshaft sensor system. The 2.0T engines are known for these particular sensor-related issues, but proper diagnosis is important before replacing parts.

Had the same symptoms recently. My Audi is at 111242 KM and last service was 2 months ago. Got it scanned and the error codes pointed to camshaft position sensor failure affecting ignition timing. The sensor testing showed intermittent voltage readings. Replaced both camshaft sensors since they are prone to fail around this mileage. Labor and parts cost me 450 Euro total. The check engine light cleared and engine runs smooth now. No more rough starts or stalling. Just make sure your mechanic checks the wiring harness too, sometimes the connection gets corroded and causes similar symptoms without needing full sensor replacement.

Thanks for the update on your A3. Your experience matches exactly what I found with my A4, these 2.0T engines often show similar symptoms when the camshaft position sensors start failing. The check engine light combined with rough running is a classic sign of sensor failure in these models. Your repair cost of 450 Euro sounds about right. I paid more because I needed that encoder wheel replaced too. Smart move getting both sensors done at once since they typically wear at similar rates. The tip about checking the wiring harness is spot-on. After my repair, I learned that corrosion in the sensor connections can trigger false engine misfire codes and similar symptoms to a bad sensor. Having the wiring inspected probably saved some from unnecessary sensor replacements. Interesting that it happened at 111242 KM, pretty close to when mine started acting up. These crankshaft and camshaft sensors seem to have a predictable lifespan on our engines. Regular testing during maintenance could help catch failing sensors before they cause major running issues.

I appreciate all the detailed feedback. Good to hear you had similar symptoms and fixed it with a sensor replacement. My situation sounds identical, rough running, stalling, and the check engine light coming on right around the same mileage. Taking it to my mechanic tomorrow for the camshaft position sensor replacement. Will ask them to inspect the wiring harness for corrosion while they're at it. The 450 Euro repair cost seems reasonable given both sensors need replacement. Nice to know the crankshaft and camshaft sensors tend to fail around this mileage. Will add sensor testing to my regular maintenance schedule to catch any issues early. Definitely beats dealing with unusual stalling and hard starts. Really helpful to confirm this is a common issue with our engines. Gives me confidence we've identified the right problem before spending money on repairs. Will update once everything is fixed.