A1 Power Loss Points to Timing Chain Malfunction

Had similar issues with a 2015 Audi A3 1.4 TFSI. The symptoms matched exactly, power loss, increased fuel consumption, and engine management light. Initial investigation pointed to engine synchronization problems between crankshaft and camshaft. The root cause was indeed a faulty crankshaft position sensor. This component is crucial for proper engine timing and fuel delivery. When it starts failing, it sends incorrect signals about crankshaft position, causing the engine control unit to mistime fuel injection and ignition. The repair involved replacing both the crankshaft sensor and checking the reference values of the camshaft sensor to ensure proper engine synchronization. It was a serious issue that required immediate attention, as continuing to drive risked potential engine damage. The symptoms you describe strongly align with sensor-related timing issues. The increased fuel consumption occurs because the engine control unit cannot optimize fuel delivery without accurate crankshaft position data. The sluggish performance is a direct result of the engine running in a safe mode to prevent damage. Would recommend getting the crankshaft sensor checked before exploring more complex issues like timing chain problems.

Thanks for sharing your experience. It sounds exactly like what I am dealing with right now. My local garage just quoted me for the crankshaft sensor replacement but I am getting a second opinion next week. Since you had this fixed, could you share how much the repair ended up costing? Also curious if the engine light or any other issues came back after the fix. The timing chain diagnosis would have been way more expensive so hoping the sensor is the actual problem like in your case.

Following up regarding costs, the total repair for my A3 came to 340 Euro including parts and labor. The crankshaft position sensor replacement fixed the issue completely and the engine light has stayed off since then. Most importantly, the mechanic confirmed the crankshaft to camshaft reference value was spot on after the repair. The engine synchronization returned to normal right after fixing the defective crankshaft sensor. My fuel consumption dropped back to normal levels and the sluggish performance disappeared completely. Much better than having to deal with timing chain issues, which would have been significantly more expensive. Worth mentioning that proper engine timing was restored immediately after the sensor replacement. It has been running smoothly for over 8 months now with no warning lights or performance issues. The timing belt and camshaft operation remain perfect since the fix. Getting that second opinion is smart, but based on the matching symptoms, you are likely dealing with the same sensor problem I had.

Just wanted to update everyone on how this turned out. Finally got the car fixed last week and wanted to share the results. Took it to another garage for that second opinion and they confirmed it was indeed the crankshaft sensor causing the misfire and timing issues. The repair cost came to 290 Euro total, which was actually less than the first quote I got. The mechanic showed me the old sensor which was clearly damaged. They also checked the camshaft timing while they were at it, and everything else looked good. Been driving for about a week now and the difference is night and day. No more engine light, power is back to normal, and fuel consumption has dropped back to what it should be. The engine synchronization is perfect now, no more sluggish performance or rough running. Really glad I did not have to deal with timing chain issues. Thanks again for the advice, it helped me push for the right diagnosis and saved me from a much more expensive repair.