RS4 Engine Stalls: Fuel Rail Pressure Issues Uncovered

Had a similar issue on my 2018 Audi S5. The symptoms matched exactly, engine stalling at idle, reduced power, and persistent check engine light. The fuel rail pressure sensor was indeed the culprit. The sensor monitors pressure in the fuel delivery system and sends data to the engine control unit. When it fails, the engine performance suffers significantly as the computer cant properly regulate fuel delivery. In my case, the repair involved replacing both the pressure sensor and the associated wiring harness since corrosion had spread. The job took about 4 hours since accessing the fuel rail required removing several components. This is considered a serious issue that needs prompt attention. Running the engine with incorrect fuel pressure can damage injectors and other components over time. The symptoms wont resolve themselves and typically worsen. Key indicators it was the pressure sensor: Engine stalling specifically at idle, Significant power loss, Rough running when cold, Diagnostic codes pointing to fuel system issues Would recommend getting a second opinion from an Audi specialist who can properly diagnose with the right diagnostic equipment. The fuel pressure sensor is a common failure point on these engines.

Thanks for sharing that detailed experience with the S5. I had these exact symptoms on my RS4 last year and also ended up replacing the rail pressure sensor. How much did the repair cost you in total? Just want to compare notes since prices seem to vary quite a bit for this job. Also curious if youve had any other sensor signal issues since the repair? My engine performance has been perfect after fixing it, but always good to know what to watch out for with these cars.

Glad to help with a cost comparison. The repair on my S5 came to 240 Euro for fixing the faulty rail pressure sensor. This was just for the sensor replacement since my wiring harness turned out to be fine, unlike what I initially suspected. Since having the rail pressure sensor signal fault fixed, the diesel engine has run flawlessly, no more stalling issues, power loss, or check engine lights. The fuel injection system works perfectly now, maintaining proper fuel pressure throughout the operating range. Its been over a year since the repair and I havent experienced any other sensor-related problems. The key is getting it diagnosed and fixed quickly when these symptoms show up to prevent strain on other fuel system components.

After hearing about your experience, I finally took my RS4 to a different mechanic who specializes in fuel injection systems. The total repair came to 380 Euro, bit more than yours but included some additional diagnostic work. The mechanic found the rail pressure sensor was definitely shot, causing the engine stalling and power issues. They completed the work in about 3 hours, and the difference was immediately noticeable, smooth idle, full power restored, and no more check engine light. Been driving for three months since the repair with zero issues. The fuel pressure is stable, and the engine runs perfectly. Really glad I got a second opinion and dealt with it properly instead of letting it get worse. Worth every cent to have it running right again.