SQ5 Fuel Pressure Problems Causing Engine Issues

Having some experience with similar issues, I encountered this exact problem on my 2014 S4 after changing the fuel filter. The symptoms you describe match perfectly, engine stalls, power loss, and check engine light triggered by fuel pressure sensor readings. The fuel system was unable to maintain proper pressure, causing engine misfires during acceleration. My workshop ran a diagnostic test which confirmed the fuel pressure regulator was functioning correctly, but the fuel pressure sensor was giving false readings after the filter change. The fix involved: Resetting the engine control unit, Recalibrating the fuel pressure sensor, Running a full system diagnostic, Test driving to confirm normal operation Total cost was 45 Euro for diagnostics and reset. The issue was resolved without needing to replace any parts. To better assist with your case, could you share: Has any recent work been done on the fuel system? What error codes is the check engine light showing? Does the problem occur more when the fuel tank is low? Are you experiencing rough idle or hesitation during cold starts? These details would help determine if your issue is similar to what I experienced or if the fuel regulator actually needs replacement.

Just had my 181256 KM service done last month. The diagnostic readings from my recent workshop visit showed consistently low fuel pressure readings across all test conditions. My mechanic tested the fuel pressure at different points in the system and confirmed a steady pressure drop, even at idle. The strange part is that the engine misfire only happens after the engine warms up fully. The check engine light initially flashed but now stays constant. Given the fuel efficiency has also dropped by about 20%, I am quite certain its the regulator rather than just sensor readings. Already tried the ECU reset but the symptoms returned within 2 days. The quoted repair cost is 320 Euro for parts and labor which seems reasonable based on what I am reading online.

Actually my initial diagnosis was off the mark. After reading your follow-up, your symptoms point much more clearly to a failing fuel pressure regulator than sensor issues. The consistent pressure drop your mechanic measured across the fuel rail is particularly telling. The warm engine misfires and 20% reduction in fuel efficiency match what I experienced before replacing my regulator. My repair cost was similar, 295 Euro parts and labor. In my case, the degraded regulator was causing: Inconsistent fuel rail pressure, Major fuel efficiency drops, Similar misfiring patterns after warm-up, Pressure fluctuations under load The workshop confirmed the diagnosis by testing pressure at different points in the fuel system. They found significant pressure variations that got worse as operating temperature increased. The 320 Euro quote sounds right given current parts costs. Make sure they test the entire fuel system after installation to verify normal pressure readings have been restored. This helps avoid repeat issues from related components that might be stressed. Would suggest having them check the fuel filter condition during the repair since you are at 181K. A clogged filter can put extra strain on a new regulator.

Based on the conversation flow, here's my conclusion as: Thanks for confirming my suspicions about the fuel pressure regulator. The symptoms match exactly what you described, especially the warm engine misfires and efficiency loss. My mechanic noticed the same pressure variations getting worse with temperature. I will go ahead with the 320 Euro repair since the price seems in line with your experience. Good tip about checking the fuel filter, I will definitely have them inspect and replace it if needed while they are working on the fuel system. Better to address any potential issues now than risk damaging the new regulator. The rough idle and check engine light have been quite concerning, so I am relieved to have a clear diagnosis and solution. Will update once the repair is completed to confirm if it resolved all the symptoms.