Black Smoke & Rough Running: Faulty Audi A2 Injectors Alert

I faced nearly identical symptoms with my Audi A3 2.0 (2002). The rich mixture and black smoke immediately pointed to fuel injector problems, and that was exactly what it turned out to be. After checking the basics like you did, I took it to a workshop where they diagnosed a faulty fuel injector. The rich fuel mixture was causing poor fuel economy and that characteristic jerking during acceleration. The repair involved: 1. Full diagnostic scan 2. Fuel injector testing 3. Replacing one defective injector 4. Cleaning the remaining injectors 5. Resetting the engine management system Total cost was 515 Euro, which included parts and labor. The check engine light disappeared immediately after repair, and both performance and fuel consumption returned to normal. To help diagnose your specific case, could you share: Current mileage, When was the last fuel system service, Does it run rough at idle too, Any other warning lights besides check engine, Type of fuel you typically use The symptoms strongly suggest injector issues, but knowing these details would help confirm if your case matches what I experienced.

Thanks for the reply. The car has 41961 KM and the last full service was done 3 months ago. Yes, it runs rough at idle too, which makes me think the fuel injector diagnosis could be spot on. The air-fuel ratio being off and rich mixture causing black smoke match my symptoms exactly. This helps narrow down the likely repair costs. I noticed the check engine light only flashes during heavy acceleration, not constantly. Premium fuel only. Will book it in for injector testing and cleaning based on your experience. Helpful to know the repair costs were reasonable compared to replacing the catalytic converter, which I feared might be damaged from running rich for so long.

Thanks for the additional details. After getting my injectors fixed on my A3, I actually had a related issue emerge a few months later, turns out the oxygen sensor had also been damaged from the extended period of rich running. The oxygen sensor plays a crucial role in maintaining the proper air-fuel ratio, and when the engine runs too rich for too long, it can get coated with excess fuel residue. In my case, the new injector was working fine, but the compromised oxygen sensor kept sending incorrect readings, leading to similar symptoms returning. The catalytic converter thankfully survived in my case, but getting the oxygen sensor replaced was an additional 180 Euro repair. Since your symptoms and vehicle age are so similar, you might want to have them check both components. The combination of flashing check engine light and rough idle strongly suggests the fuel mixture is still not optimal. Considering your low mileage and recent service, focusing on the fuel delivery and monitoring systems makes the most sense. If they do find injector issues, definitely have them inspect the oxygen sensor condition while everything is apart, it could save you a second repair visit like I had. The good news is your quick response to the symptoms should prevent any permanent damage to your catalytic converter or engine components.

Thank you everyone for your suggestions. Just got back from the workshop and wanted to share how it turned out. They confirmed the fuel injectors were indeed the main culprit, two were faulty and needed replacement. The total bill came to 680 Euro which included: Replacing 2 fuel injectors, Professional cleaning of the other injectors, New oxygen sensor as a preventive measure, Full system diagnostics The mechanic showed me the old injectors which were badly clogged. The oxygen sensor was also starting to fail, so glad they caught that before it caused more issues. The catalytic converter checked out fine, thankfully. After the repair, the engine runs perfectly smooth again. No more black smoke, jerking, or check engine light. Fuel consumption is back to normal too. Really relieved it wasnt something more serious. Thanks again for helping me diagnose this, saved me from worrying about more expensive repairs and helped me know what to expect at the workshop.