Audi A6 Rough Idle Points to Failing TDI Injectors

I had a similar issue with my Audi A4 2.0 TDI from 2008. With some experience working on diesel engines, I recognized these symptoms immediately. The check engine light and rough running turned out to be a loose connection at the wiring harness going to one of the coil packs. The engine hesitation and jerky acceleration were classic signs of coil failure, but in my case, it was just the connection that needed fixing. Initially thought I needed to replace the entire ignition coil setup, but my mechanic found the actual issue during diagnostics, a damaged wire and loose plug connection near one of the coils. Total repair cost was 95 Euro, mostly labor for diagnosing and fixing the connection. Before jumping to conclusions about needing new coils, could you share: Have you had the diagnostic codes read? Does the engine hesitation happen at specific RPM ranges? When was your last maintenance service? Any recent work done on the engine? This information would help determine if you are facing the same electrical connection issue or if you actually need to replace coil packs.

Thanks for looking into this. My last service was only 2 months ago at 76320 KM. After reading your description, I checked with a diagnostic tool and got error code P0201, pointing to injector circuit issues. The engine hesitation seems worse during cold starts and really noticeable between 1500-2000 RPM. The vehicle diagnostics suggest it might not be just the coil packs after all. The ignition system was checked during my recent service, but they didnt find any obvious issues with the spark plugs or connections at that time. The rough running and stalling have gotten progressively worse over the last few weeks. I will have the wiring harness connections checked based on your experience. Thanks for sharing the tip about checking the electrical connections before replacing parts.

Just had my mechanic look deeper into those injector circuit issues you mentioned. For my car, error code P0201 initially made us check the wiring too, but turned out we had a failing injector that was causing similar symptoms to what you describe. A proper vehicle diagnostics session revealed the injector was actually misfiring intermittently, creating that rough running sensation especially during cold starts. The coil packs and spark plugs were fine, but the faulty injector was disrupting the proper fuel delivery. After replacing the problematic injector (280 Euro including labor), all symptoms disappeared, no more engine stalling, rough running, or jerking during acceleration. The check engine light also cleared up. Given your symptoms match my experience so closely, especially that specific RPM range where it acts up, I would suggest having your injectors tested. While checking wiring connections is a good first step, the error code combined with the cold start issues strongly points to injector problems. Consider getting a fuel system cleaning service first, sometimes carbon buildup can cause similar symptoms and its cheaper than replacing injectors. But if that doesnt help, be prepared for injector replacement.

Thanks everyone for the helpful responses. Just wanted to update on my A6 situation. Had it checked at a repair shop yesterday and you were right about the injector issue. They ran vehicle diagnostics and found two problems: a faulty injector causing the misfire and a damaged wire in the wiring harness. The engine stalling and rough running were exactly as described, worse during cold starts and in that 1500-2000 RPM range. They replaced the bad injector and repaired the wiring harness connection. Total cost came to 410 Euro for parts and labor. The car runs perfectly smooth now, no more jerking during acceleration or rough idling. The check engine light is finally off too. Really glad I didnt jump straight to replacing coil packs without proper diagnosis. Thanks again for steering me in the right direction with the injector suggestion. After this experience, definitely learned the importance of getting proper diagnostics before replacing parts. Will keep an eye on how it performs over the next few weeks, but so far the repair seems to have completely resolved the issues.