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rainereis33

Audi S3 Fuel System Failure Causes Engine Stalling

My 2001 Audi S3 is showing serious fuel system issues. The engine keeps stalling at idle and the check engine light stays on. After reading the error codes, I suspect wrong fuel might be the culprit. Has anyone experienced similar symptoms and gotten them fixed? I am particularly interested in hearing about workshop experiences and repair solutions. My main concern is the fuel mixture causing these problems. Any tips before I take it to a shop would be helpful.

4 comment(s)

erwintiger75

Having owned a 2003 Audi A3 with a similar gasoline engine, I can relate to your fuel system troubles. With some experience working on Audis, the symptoms you describe match what I encountered. My engine also had stalling issues and the check engine light was constantly illuminated. After multiple fuel mixture problems, I discovered the root cause was a faulty connection in the fuel pump wiring harness. The workshop found that poor electrical connectivity was causing irregular fuel delivery to the combustion chamber. The repair involved replacing damaged cables and connectors, which resolved both the stalling and check engine light issues. Total cost was 95 Euro for parts and labor. Since the fix, the engine knock disappeared completely and fuel quality no longer seemed to affect performance. To provide more specific advice, could you share: Current mileage, Type of fuel you typically use, When the problems first started, Any unusual sounds from the engine, Whether the issues occur more during cold starts These details would help determine if your S3 has similar underlying causes to what I experienced.

rainereis33 (Author)

Thanks for the detailed repair suggestion. Just checked, currently at 18241 KM and had the last service done only 2 months ago. The fuel system issues started showing right after I used a different gas station than usual, which makes me suspect fuel quality could be the problem. After reading about similar cases, I tried adding some fuel additives to clean the combustion chamber, but the stalling persists. The mechanic during my last service mentioned the fuel economy was great, so this sudden change is quite concerning. Before taking it to the workshop, I am wondering if draining the fuel tank completely might help resolve the issue of potentially wrong fuel being used?

erwintiger75

Based on the mileage and recent service history, draining the tank might be overkill. When my A3 showed these symptoms, I first tried running the tank nearly empty and refilling with high-quality fuel. This helped identify if the fuel mixture was truly the issue without the expense of a complete system drain. The connection between using a different gas station and the onset of problems suggests contaminated fuel could be disrupting your fuel system. However, since adding fuel additives did not resolve the stalling, the issue might extend beyond just fuel quality. My car displayed similar behavior when the fuel filter was clogged, restricting proper flow to the combustion chamber. Before proceeding with a costly tank drain, consider these steps that worked in my case: Run the tank down to about 1/4 full, Add a professional-grade fuel system cleaner, Fill with high-quality fuel, Monitor for any improvements over 2-3 tank cycles If symptoms persist after these steps, the problem likely involves other fuel system components such as sensors or the fuel pump, similar to what I experienced with my faulty wiring harness. Would you be able to confirm if the check engine light shows any specific fuel trim related codes? This information helped diagnose my A3s issues more accurately.

rainereis33 (Author)

Thank you for sharing those troubleshooting steps. I checked and the engine is showing code P0171, which points to a lean fuel mixture. After trying your suggested method of running the tank low and refilling with premium fuel, the engine knock has actually gotten worse, especially during cold starts. Given that the fuel contamination seems more serious than initially thought, I will skip further DIY attempts. Already scheduled an appointment with a repair shop for next week to have the entire fuel system inspected. The fuel filter has never been changed in my ownership, so that could definitely be contributing to the problems. Will make sure to request they check the fuel pump and wiring harness too, since your experience with similar symptoms proved these could be the underlying cause. Hope the fix will be as straightforward as your 95 Euro repair, though I am prepared for a more extensive service given the age of my fuel system components.

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