Audi A2 Fuel System Issues: Diagnosis and Solutions

I had a very similar issue with my Audi A3 2003 gasoline model. As someone with some experience working on cars, I initially thought it was a fuel delivery problem when experiencing those exact symptoms, rough idle, stalling, and jerking during acceleration. After checking the usual suspects like spark plugs and fuel filter, I took it to my workshop. They diagnosed a loose connection at the wiring harness leading to the fuel pressure sensor. The engine misfire was actually caused by the sensor sending incorrect readings to the ECU, which then messed up the fuel injector timing. The fix was relatively straightforward, they repaired the damaged cable and plug connection for 95 Euro. The symptoms disappeared completely after that. Before suggesting more specific checks, could you share: Current mileage on your A2, When was the last fuel system service done, Are there any other warning lights besides the check engine light, Does the problem get worse when the engine is cold or warm The symptoms you describe could point to several fuel delivery related issues, so these details would help narrow it down.

Last service was 1200km ago where they changed oil and filters. Currently at 137599km. The check engine light started appearing more often after cold starts. I noticed the fuel injectors making unusual clicking sounds lately. After warming up, the engine stalling becomes less frequent but the misfire is still noticeable when accelerating. No other warning lights besides the check engine light. Will try checking the wiring connections first based on your experience. Thanks for the repair cost reference, good to know it might be a simpler fix than expected if its also just a wiring issue.

Thanks for those details. Based on what you described, especially the clicking from the injectors, this sounds very familiar to what I experienced. However, after fixing the wiring on my A3, the clicking persisted and I ended up having a bigger fuel system issue. The frequent cold start problems combined with clicking injectors often points to inconsistent fuel pressure. In my case, the fuel pressure sensor wiring was just the first symptom of a failing fuel pump. After about 2 weeks, the rough idle and fuel delivery problems came back worse than before. The complete repair ended up involving: New fuel pump assembly (380 Euro), Fuel pressure sensor replacement (120 Euro), New fuel filter (45 Euro) My advice would be to have a proper fuel pressure test done. The clicking injectors at 137000km could indicate the pump is struggling to maintain consistent fuel pressure. While checking the wiring is a good first step, be prepared that the root cause might be the pump itself. The improved performance after warm-up matches what I experienced with a weakening fuel pump, they tend to work better once everything reaches operating temperature, but the underlying fuel delivery problem remains.

Following everything thats been shared, Id say my situation is probably heading toward a fuel pump replacement given how similar the symptoms are. Those clicking injectors combined with the cold start issues really match what you went through. Im going to take it in next week and ask them to start with checking the wiring and running a fuel pressure test. At least now I can explain the symptoms better and have a realistic idea of potential costs, anywhere from 95 Euro for wiring up to 545 Euro if the whole fuel delivery system needs work. The warm engine behavior definitely makes me think the fuel pump might be on its way out, just like in your case. Ill make sure to update this thread once I get it diagnosed and fixed in case anyone else runs into similar fuel system problems with these models. Makes sense to tackle this soon before I end up completely stranded somewhere due to fuel delivery failure. Better to fix it properly now than risk more engine misfires and potential damage.