Audi SQ5 Fuel Rail Issues Causing Stalling & Power Loss

Having some experience working on Audi engines, I faced nearly identical symptoms with my S4 3.0T from a similar production year. The fuel rail pressure sensor was indeed the culprit, causing unstable idle and power delivery issues. Initially thought it might be a fuel pump problem, but the diagnostic codes pointed clearly to the pressure sensor. After replacing the fuel rail pressure sensor at a specialized workshop, all issues disappeared completely. The repair cost me 240 Euro including parts and labor. The pressure sensor is crucial for the engine management system to regulate proper fuel injection. When it fails, it sends incorrect readings to the ECU, causing the symptoms you describe. To provide more specific guidance, could you share: Build year of your SQ5, Current mileage, Any modifications to the fuel system, When the symptoms first appeared, Whether the check engine light is constant or intermittent This information would help determine if your case matches mine and whether other components of the fuel rail system should be inspected.

Thank you for sharing your experience. My SQ5 has 137576 KM on the clock with the last service completed 3 months ago. The engine light stays constant, and symptoms started two weeks ago without any prior warning. The fuel pressure sensor signal issue seems to match my symptoms exactly. No modifications have been made to the fuel system, everything is stock. Based on your repair cost estimate of 240 Euro, that seems like a reasonable fix compared to what I was worried it might be. Would you recommend checking the entire fuel rail assembly while the sensor is being replaced, or is the sensor typically an isolated failure point?

Based on the mileage and symptoms you described, it definitely mirrors what I experienced. With your SQ5 being stock like my S4 was, the fuel rail pressure sensor is very likely the root cause, especially given the sudden onset of symptoms. In my case, the rest of the fuel rail assembly was perfectly fine. The pressure sensor tends to be an isolated failure point in these engines. However, while the technician had everything opened up, they did a visual inspection of the entire fuel injection system and fuel rail components, it only added about 15 minutes to the job. The constant check engine light matches my experience too. Mine stayed on until the sensor was replaced, then cleared immediately after the repair. Engine performance returned to normal right away, with stable idle and full power restored. One tip from my repair, make sure they clear all fuel pressure from the system before starting work. A proper technician will know this, but its worth mentioning since improper fuel rail pressure release can cause issues during the repair. Looking at your timing, symptoms starting two weeks ago with recent servicing, this further supports the pressure sensor diagnosis rather than a broader fuel system problem. The repair should resolve your engine performance issues completely.

Thanks for the detailed insights. My mileage is actually 137500 KM and I just had service 3 months back. The check engine light stays on constantly, and these symptoms only showed up 2 weeks ago with no warning signs before that. The fuel pressure sensor situation you described matches my symptoms perfectly. Since my car is completely stock with no fuel system modifications, your repair cost estimate of 240 Euro seems much more reasonable than what I was fearing it might be. Makes sense about the sensor being an isolated failure point rather than needing to replace the whole fuel rail. Though I will ask the shop to inspect the entire fuel rail assembly while they have it open, just to be thorough. Good tip about making sure they properly release the fuel pressure before starting the work, I will mention that specifically when I take it in. Based on the matching symptoms and similar engine configuration, I feel pretty confident moving forward with the pressure sensor replacement. Will book it in this week and hopefully get back to normal engine performance soon.