Rough-Running Audi S1: Knock Sensor Warning Signs

I experienced something very similar with my 2014 Audi A1. As someone with moderate experience working on cars, I initially thought it might be more serious when the check engine light came on and I noticed rough idling. The workshop ran diagnostics and found it was actually just a loose connection to the knock sensor. The cable had worked itself loose over time, causing erratic readings. This explained both the warning light and the poor fuel efficiency, as the engine management system was getting incorrect knock sensor data and running a conservative fuel mixture as a safety measure. The fix was straightforward, they cleaned the connector, secured it properly, and cleared the error codes. Total cost was 95 Euro including diagnostics. Engine has been running smoothly since, with normal fuel consumption restored. Could you share some additional details about your S1: Current mileage, Whether the check engine light is constant or intermittent, Any unusual sounds when the engine is running, When you first noticed these symptoms This information would help determine if your issue is similar to what I encountered.

Just had my car serviced last week at 155699 KM. The ignition timing and engine knock issues turned out to be more complex than expected. After further inspection, the mechanic found that both the knock sensor and ignition coils needed replacement. The malfunction indicator persisted even after cleaning the connectors. Total repair cost came to 550 Euro, but the check engine light is now off and fuel efficiency has returned to normal.

Thanks for the update on your S1. My A1 situation initially seemed similar, but you definitely had a more serious underlying issue. Good thing you had it properly checked, when knock sensors fail completely like in your case, it can lead to engine damage if left unchecked. The combination of faulty knock sensor and ignition coils explains why the warning light stayed on even after cleaning the connections. When both components are compromised, the engine management system cant properly adjust ignition timing, leading to those efficiency and performance issues you experienced. The 550 Euro repair cost sounds reasonable for replacing both components, especially considering the improved engine performance and restored fuel efficiency. In my case, I was lucky it was just a connection issue, but your experience shows why its important to get these symptoms properly diagnosed rather than assuming its always a simple fix. Did you notice any improvement in the overall engine smoothness after the repairs? My guess is the new ignition coils made a noticeable difference in how the engine runs.

Thanks everyone for the helpful responses. Yes, there's been a massive improvement in how the engine runs now. The rough idle is completely gone and it feels much smoother during acceleration. The auto repair shop did a great job identifying both issues, I initially thought it was just the knock sensor causing the poor performance, but the faulty ignition coils were definitely contributing to the problem too. The malfunction indicator has stayed off since the repair, and my fuel consumption is back to what it should be. While 550 Euro seemed steep at first, its definitely worth it for the peace of mind and restored performance. Really glad I didn't wait any longer to get it fixed, as the mechanic mentioned ignoring the ignition timing issues could have led to more expensive problems down the line.