Audi A7 Knock Sensor Woes Impact Performance

Having some experience working on Audis, I encountered similar malfunction indicator issues with my 2013 Audi A6 3.0T last year. The symptoms were nearly identical, poor performance, rough idling, and decreased fuel efficiency. After initial diagnostics, it turned out to be a loose wiring connection to the knock sensor. The cable had deteriorated over time, causing intermittent signal issues. The repair involved replacing the wiring harness and properly securing all connections, which cost 95 Euro including labor. The fix completely resolved all the engine problems. The car went back to running smoothly with normal fuel consumption, and the check engine light disappeared. Before jumping to conclusions though, could you provide: Current mileage, Any other warning lights, Whether the issues appeared gradually or suddenly, If you notice any unusual engine sounds, Recent maintenance history This information would help determine if your situation matches what I experienced or if there might be other underlying issues causing these car problems. While a faulty knock sensor is a common culprit for these symptoms, proper diagnostics are crucial to avoid unnecessary parts replacement.

My car has 150525KM on the odometer with the last service done at 145000KM. I can confirm there are no other warning lights besides the check engine light. The issues started gradually over the past month. Lately, I have noticed a faint ticking noise from the engine bay, especially during cold starts. Looking at additional auto repair suggestions would be helpful since I want to be certain before replacing any parts. The engine knock seems most noticeable during acceleration.

Thanks for providing those details. In my case with the A6, I also noticed that ticking noise during cold starts before the problems escalated. Given your description of gradually worsening symptoms and engine knock during acceleration, this strongly points to knock sensor issues rather than just a wiring problem like I initially had. After fixing my wiring harness, the problems temporarily improved but returned after a few weeks. The full knock sensor replacement ended up being necessary, costing 280 Euro with labor. Post-replacement, both the ticking noise and engine knock completely disappeared, fuel efficiency returned to normal, and the check engine light stayed off. Your mileage and symptoms align very closely with when my knock sensor failed. The gradual performance decline is typical of a failing sensor rather than a sudden wiring issue. A proper diagnostic scan would confirm, but based on my experience with the same engine, I would recommend getting the knock sensor replaced rather than just checking connections. Poor fuel efficiency combined with knocking sounds during acceleration are classic indicators that the engine timing is being affected by faulty knock sensor readings. The ECU is likely running a conservative timing map to protect the engine, explaining the performance issues youre experiencing.

Thank you for the detailed follow-up. The symptoms you described with the ignition timing issues make me feel more confident about proceeding with the knock sensor replacement. The engine knock during acceleration and ticking noise match exactly what I experienced leading up to my issues. Based on both your experience and my mechanics initial assessment, I plan to move forward with the repair. Just to be safe, I will ask them to perform a full diagnostic scan first to confirm the malfunction indicator is indeed triggered by the knock sensor before replacing it. Given the similar mileage and progression of warning signs, the 280 Euro repair cost seems reasonable if it resolves all these issues. The gradual decline in performance and fuel efficiency really had me worried about potentially major engine problems, so I appreciate you sharing your experience with an almost identical situation. Will proceed with the repair next week and hopefully get back to normal performance without any warning lights or concerning sounds.