VW Up Fuel Regulator Issues, Symptoms and Solutions

As someone with some mechanical experience, I encountered a similar issue with my 2013 VW Polo, basically the same fuel system setup as your Up. The symptoms were identical: stalling at idle, reduced power, and an illuminated check engine light pointing to fuel delivery problems. My fuel pressure regulator was indeed the culprit, but the diagnostic process revealed the issue started after a routine fuel filter change. The workshop found the fuel system needed proper bleeding after the filter replacement. The entire fuel rail had to be checked for proper pressure regulation. The fix involved: Proper system diagnosis using fuel pressure testing, Bleeding the fuel system thoroughly, Verifying fuel regulator operation, Clearing the check engine light codes Total cost was 45€ for the diagnostic and repair work. The car has been running perfectly since, with restored fuel efficiency and proper idle. Before suggesting specific solutions, could you share: Have you recently had any fuel system maintenance done? What error codes is your check engine light showing? Does the problem get worse when the engine is warm? Is your fuel consumption notably higher than usual? This information would help determine if your issue matches what I experienced or if there might be other fuel system components involved.

Last service was only 2000km ago and included a fuel filter replacement. The check engine light started showing P0171 (system too lean) about a week after. The rough idle gets significantly worse when the engine reaches operating temperature, especially in stop and go traffic. I noticed the fuel efficiency dropped from about 5.2L/100km to nearly 7L/100km since these issues started. Local parts supplier quoted 85€ for a new fuel pressure regulator, but I want to be certain before buying parts. The fuel pump seems to make a louder whining noise than usual too, which makes me wonder if theres a bigger issue in the fuel delivery system.

Thanks for providing those details, the symptoms line up exactly with what I experienced. After my fuel filter change, I also got the P0171 code and noticed the same fuel pump noise. The increased fuel consumption and rough idle after warming up are telltale signs of pressure regulation issues in our VW fuel systems. In my case, while the fuel pressure regulator was the main culprit, the technician found trapped air in the fuel lines was causing the pump to work harder, explaining the whining noise. The engine misfire and rough idle got worse with heat because the trapped air expanded, further disrupting proper fuel delivery. Important findings from my repair: The fuel system needed proper bleeding after filter replacement, Pressure sensor readings confirmed irregular fuel rail pressure, The old regulator showed signs of internal diaphragm wear, The fuel pump noise disappeared after fixing these issues Given the identical symptoms and timing after the filter change, I strongly recommend getting a fuel pressure test done before replacing parts. In my case, proper bleeding and regulator replacement completely resolved the issues, and the fuel consumption returned to normal within two tanks. The 85€ parts quote is reasonable, but consider having a professional diagnose and repair it, proper bleeding of the fuel system requires specific tools and procedures on these VWs.

Thanks for the input. After reading about your experiences, I feel much more confident about the diagnosis. The similarity between our situations, especially the timing after the fuel filter change and the P0171 code, is quite striking. I will get the fuel pressure tested first to confirm, but based on the rough idle, pressure drop symptoms, and engine misfire issues you described, it seems my fuel pressure regulator is definitely the likely culprit. The trapped air explanation also makes sense given the fuel pump noise. I decided to book an appointment with a shop that specializes in VW fuel system diagnostics rather than attempting the repair myself. While 85€ for the regulator part is reasonable, I want to ensure the system gets properly bled to avoid any recurring issues. Will update once I get it fixed. Really appreciate all the detailed diagnostic steps and repair insights shared here, saved me from potentially replacing wrong parts or missing important repair procedures.