RS3 Fuel System Issues Causing Engine Stalls

I had a very similar issue with my 2020 S3 last summer. With some experience working on Audi engines, I recognized the symptoms you described, engine stalling and rough running could indeed point to fuel mixture problems. In my case, the root cause was a faulty wiring connection to the fuel pressure sensor. The workshop diagnosed a cable connection issue that was causing incorrect readings and making the engine run with an improper fuel mixture. The repair involved replacing the damaged wiring and properly securing the connector. Total cost was 95 Euro for parts and labor. The engine knock disappeared completely after the fix, and fuel economy returned to normal levels. No more stalling issues since then. Would you mind sharing: Any unusual sounds from the engine? When did these symptoms first appear? What type of fuel do you typically use? Have there been any recent maintenance work done? Reading the error code would definitely help narrow down the exact cause. There could be fuel contamination or other fuel system issues at play, so getting a proper diagnosis is important before replacing parts.

Last service was done at 38293 KM. Taking my car to a workshop next week since the current symptoms match what you described. The fuel quality has been consistent as I only use premium grade. The rough running and stalling started about 2 weeks ago, accompanied by a slight engine knock especially when cold. Recently noticed a 20% drop in fuel economy. No odd sounds besides the knock, and no maintenance was done in the past 3 months. Will share the error codes once I get them read. Thanks for the insight about the wiring, will have them check the connections to the fuel pressure sensor first.

Thanks for the additional details. Given your description, it sounds even more similar to what I experienced. The knock during cold starts combined with increased fuel consumption strongly points to a fuel mixture issue in the combustion chamber. In my case, the faulty sensor wiring caused the ECU to receive incorrect readings, leading to a rich fuel mixture. The error code was P0190 which indicates a fuel rail pressure sensor circuit malfunction. Have you noticed any of these additional symptoms I had: Rough idle gets worse after the engine warms up, Occasional hesitation during acceleration, Black smoke from exhaust Beyond checking the fuel pressure sensor wiring, ask them to inspect the fuel filter as well. A clogged filter can cause similar symptoms and is a common failure point at around 40000 KM. The 20% drop in fuel economy matches what I saw before getting it fixed. The wrong fuel mixture was causing incomplete combustion. After the repair, consumption returned to normal within one tank. Keep us updated on what the workshop finds. The diagnostic should reveal if its the same sensor issue or something else in the fuel delivery system.

Thanks everyone for the suggestions. Just got back from the workshop and wanted to share what they found. Turned out the fuel pressure sensor wiring was indeed the culprit, exactly as suggested. The error code was P0190, matching what others experienced. The repair cost came to 120 Euro including diagnostics. They found corroded terminals at the sensor connector causing incorrect fuel mixture readings. After replacing the wiring harness and cleaning the connector, the engine knock disappeared completely and idle is smooth again. Fuel economy has already improved on the drive home. The combustion chamber sounds much healthier now without the knocking. No more stalling issues either. Really glad I didnt need any fuel additives or major components replaced. Appreciate the advice about checking the sensor wiring first. Saved me from potentially replacing parts unnecessarily. Will keep monitoring the fuel consumption over the next few tanks to ensure everything stays normal.