Audi A3 Engine Stalls & Power Loss: Fuel System Fix

I had nearly identical symptoms with my 2015 Audi A4 2.0 TFSI about a year ago. Having some experience with fuel injection systems, I first thought it was just a sensor issue, but it turned out to be more serious. The rough idling and power loss were exactly what I experienced. After proper diagnostics, the car sensors indicated a high pressure fuel pump failure. This component is critical for proper fuel injection and engine performance. The repair included: Complete diagnostics, Replacement of the high pressure pump, System pressure testing, New fuel pressure regulator, Car maintenance reset Total cost was 1510 Euro and took about 2 days to complete. Since the repair, the car has been running perfectly with no recurring issues. Before suggesting anything specific for your case, could you share: Any unusual sounds when starting the engine? Does the problem get worse after the engine warms up? Have you noticed increased fuel consumption? Any recent car maintenance done before this started? Did you get any specific error codes from the check engine light? This information would help determine if your A3 is facing the same issue my A4 had.

Thanks for the detailed analysis of the fuel system issues. I just had my car serviced at 40842 KM last month, and they did a full inspection without noting any problems. Since your description matches my symptoms exactly, I will have my mechanic check the high pressure fuel pump and regulator. The rough idling started quite suddenly and is most noticeable when the engine is cold. My fuel economy has definitely gotten worse in the past week. Getting about 20% higher consumption than normal. Will update once I have the diagnostic results.

Thanks for the additional details. Your symptoms align even more closely with what I experienced, especially the cold start rough idling and increased fuel consumption. In my case with the A4, these were classic signs of a failing high pressure fuel pump. The sudden onset and the timing just after a service inspection is also familiar. The fuel system components can fail quite abruptly, even shortly after passing inspection. Car maintenance records showed my pump was still within normal parameters during the previous check. A quick tip from my experience: when taking it to the mechanic, ask them to specifically check the fuel pressure readings at different RPMs. This helped identify the exact problem with my car and prevented unnecessary parts replacement. The fuel efficiency dropped significantly because the system wasnt maintaining proper fuel injection pressure. The 20% increase in consumption you mentioned matches what I saw before the repair. After fixing the pump and regulator, my fuel economy returned to normal within one tank of fuel. One thing worth noting, if this is indeed the same issue, continuing to drive with these symptoms risks causing engine misfire and potential damage to other components. I would prioritize getting it checked soon.

Thanks for the insights on fixing fuel system problems. Given how similar my symptoms are to your A4 case, especially with the cold start issues and 20% higher fuel consumption, I will definitely have my mechanic focus on the high pressure fuel pump and regulator first. Its concerning that these components can fail so suddenly even right after a service, but at least I know what to look for now. I will make sure they check the fuel pressure at different RPMs during diagnostics like you suggested. Planning to take it in tomorrow since I dont want to risk damaging other engine components. The repair cost you mentioned (1510 Euro) helps set my expectations for the work. Will update the forum once I get the diagnostic results and repair completed. Hopefully it will help others who encounter similar fuel injection issues with their vehicles.