Audi A2 Diesel: Power Loss & Stalling, Fix Guide

Had almost the exact same issue with my 2006 Audi A3 diesel last year. I have some experience working on diesels, mainly basic maintenance and troubleshooting. The check engine light came on and the engine started running really rough, especially during acceleration. After a few days, it got worse with unusual stalling. The workshop diagnosed a faulty fuel injector that was causing irregular fuel delivery. The repair involved: Complete diagnosis with injector testing, Replacement of one defective injection valve, System cleaning and calibration, New fuel filter as preventive maintenance Total cost was 515 Euro including parts and labor. The car has been running smoothly since the repair, with no check engine light or power issues. Could you share: Current mileage on your A2? When was the last fuel filter change? Any recent work done on the fuel system? Does the problem get worse with a full tank? This info would help confirm if you are dealing with the same injector issue. The symptoms match exactly what I experienced, but its worth checking these details to be certain.

Last service was done at 49841 KM which showed everything was fine with the air-fuel ratio and fuel injection system. The throttle body was also cleaned during this maintenance visit. Based on these symptoms appearing right after a routine service, the catalytic converter should be checked first since its failure often triggers similar issues and the check engine light. My mechanic previously cleared fault codes but they came back within days. Wonder if anyone else experienced issues specifically after routine maintenance? The quote I got for diagnostic testing is 180 Euro.

Thanks for those details. That's interesting because my A3 also started showing similar symptoms shortly after routine maintenance. In my case, while the fuel injector was initially suspected, it turned out the real culprit was a failing throttle body sensor causing an incorrect air-fuel ratio reading. The symptoms appeared gradually: First the check engine light, Then rough idle, Finally power loss during acceleration The rich mixture condition triggered by the faulty sensor was actually damaging the catalytic converter over time. The diagnostic revealed multiple error codes related to the intake manifold and throttle position sensor. The final fix required: New throttle position sensor (290 Euro), Cleaning the intake manifold (120 Euro), System recalibration (90 Euro) Before you spend money on major components, have them check the sensor connections and throttle body thoroughly. Sometimes carbon buildup after cleaning can cause similar issues. Ask them to specifically monitor the air-fuel ratio values during diagnostics. This could save you from unnecessarily replacing expensive parts like the catalytic converter if the root cause is actually in the engine management system.

The diagnostic quote of 180 Euro seems reasonable given the complexity of these issues. Based on everyone's feedback, I will have them check the following during diagnosis: Fuel injector performance and timing, Mass airflow sensor readings, Throttle position sensor values, Catalytic converter condition, Intake manifold for any post-cleaning issues The symptoms appearing right after maintenance make me suspect the throttle body sensor or intake system rather than major fuel system components. The fault codes returning so quickly after being cleared also points to a sensor issue rather than the catalytic converter. I will update the thread once I get the diagnostic results. Thanks for all the input, especially regarding checking the engine management system before replacing expensive parts. I had my fuel injection system inspected during the last service but will have them verify all connections and sensors again. Just booked the diagnostic appointment for next week. Hoping for a simple sensor fix rather than major component replacement, but at least I now have a better idea of potential costs and repair options.