Audi TT Rough Idle Points to Bad Camshaft Sensor

I had a very similar issue with my 2015 Audi A5 with the 2.0T engine. With some basic repair experience, I managed to diagnose it but needed professional help for the fix. Started with rough idling and sluggish acceleration, and the check engine light came on intermittently. The timing issues got worse over about two weeks, especially during cold starts. The workshop found that the camshaft position sensor was giving incorrect readings due to a damaged wiring harness connector. The repair involved replacing the wiring harness section and the sensor connector. Total cost was 95 Euro including parts and labor. Since the fix, the engine runs smoothly with no more timing issues or starting problems. To better assist with your situation, could you share: Current mileage on your TT, Are you getting any specific error codes, Does the rough idling happen more during cold starts or when the engine is warm, Have you noticed any unusual sounds from the crankshaft area These details would help determine if your issue matches what I experienced with my A5. The symptoms sound very similar, but best to confirm the exact cause before replacing parts.

Last serviced at 166351KM. The rough idling happens consistently now, regardless of engine temperature. Getting error code P0340 related to camshaft sensor malfunction. Recently noticed a distinct ticking sound from the upper engine area that wasnt there before. Looking at the diagnostic data, the camshaft position readings are erratic, which aligns with a failing sensor. The engine struggles more during cold starts and takes longer to stabilize. My mechanic recommended replacing both the camshaft sensor and checking the wiring harness since corrosion damage is common in this area. Quoted repair cost is around 280 Euro for parts and labor. Just wanted to confirm if this sounds reasonable before proceeding with the work.

Thanks for sharing those details, that P0340 code and the symptoms you describe perfectly match what I experienced with my A5. The ticking sound you mention was also present in my case, and it disappeared completely after the repair. The 280 Euro quote seems reasonable considering they are checking the wiring harness too. In my case, I initially only replaced the sensor (95 Euro) but had to go back when they discovered the wiring harness damage. The total ended up being more than if I had done both at once. Based on the erratic camshaft position readings and the engine misfire symptoms you described, tackling both components simultaneously is the smart approach. My sensor failure started similarly, inconsistent readings that got worse over time, leading to more severe timing issues and rough idling. Given your mileage, its definitely worth having the wiring harness inspected while they are in there. The corrosion typically affects the connector pins first, causing intermittent sensor readings before complete failure. After my repair, the engine performance returned to normal immediately. The rough idling and cold start issues were completely resolved, and power delivery became smooth again. Would definitely recommend proceeding with the proposed fix.

Thanks for the detailed input. Really helpful to hear about similar experiences, especially with the matching P0340 error code and comparable symptoms. Going to proceed with the full repair including both the sensor and wiring harness inspection for 280 Euro. Makes sense to address both components at once rather than risk having to do a second repair later. The timing issues and rough idling have become too problematic to ignore, and the erratic camshaft position readings clearly point to a sensor failure. The ticking noise from the upper engine area definitely has me concerned, so better to fix this properly now before it potentially causes more serious engine problems. Will update once the repair is complete to confirm if it resolves all the symptoms. The automotive sensor replacement and wiring check should hopefully eliminate the check engine warnings and restore normal engine performance. Just hoping no additional issues are found during the repair.