VW Polo Diesel Stalling: Fuel System Trouble Alert

Having some experience with diesel engines, I faced almost the same issue with my 2003 VW Golf diesel. The symptoms you describe sound very familiar, especially the stalling at idle and engine warning light. In my case, the problem was traced to a faulty wiring connection at the fuel system sensor. The wrong fuel or fuel contamination was initially suspected, but after thorough diagnostics, the workshop found that a cable connection had deteriorated, causing irregular readings in the combustion chamber. The repair involved: Complete diagnostic scan, Inspection of the fuel system components, Replacement of the damaged wiring connector, System reset Total cost was 95€ including labor and parts. Before jumping to conclusions, could you share: Which error codes you pulled? Does the engine knock when running? Did you notice any smoke from the exhaust? What type of fuel station did you last use? This information would help determine if your issue matches what I experienced or if it might be something different in the fuel system.

Thanks for the detailed reply. The error codes I got were P0190 and P0087, which point to fuel pressure issues. The engine has a slight knock when cold but runs smoother once warmed up. There is some black smoke when accelerating hard. To answer the fuel station question, it was just a regular station but the fuel quality might have been questionable since it was a really cheap one. I did my last service 3000km ago at 92858km where they changed all filters including the fuel filter. After reading about your wiring issue, I checked all visible connections but they seem fine. I am starting to think either contaminated fuel or a failing fuel pressure sensor could be causing these problems in my combustion chamber. Would adding fuel additives help clean the system, or should I go straight to a diagnostic check?

Based on those error codes and symptoms, this looks more serious than my initial wiring problem. While our VW diesels share similar symptoms, your black smoke and pressure-related codes suggest a different root cause in the fuel system. Those codes typically indicate issues with either the fuel pressure sensor or the fuel pump itself. Given that your fuel filter was recently changed, contaminated fuel could have damaged these components. In my case, adding fuel additives didnt fix the underlying issue, it just masked the symptoms temporarily. My recommendation based on this new information: Skip the additives for now, Get a professional diagnostic done first, Consider draining the fuel tank if contamination is confirmed, Have the fuel pressure sensor tested My cars repair costs ended up higher than initially shared when similar symptoms developed later, around 450€ when the fuel pump needed replacement. The wrong fuel or contaminated fuel can seriously impact multiple components in the fuel system, especially in these sensitive diesel engines. Does the engine respond normally to throttle input, or does it feel sluggish? This could help determine if the fuel mixture is actually reaching the combustion chamber properly.

Thanks for the input. After comparing my symptoms with your experiences, I decided to take it to a workshop for proper diagnostics rather than experiment with fuel additives. The black smoke and engine knock when cold, combined with those fuel pressure codes, definitely point to something more serious than just bad fuel. Makes sense that contaminated fuel could have damaged the pressure sensor or pump, especially since these symptoms started right after that questionable refueling. The fuel economy has also dropped noticeably which supports this theory. At least the fuel filter is new, so that eliminates one potential cause. Will book it in next week and report back with what they find. Hoping its just the sensor at 450€ rather than the whole pump assembly. Learned my lesson about choosing cheaper fuel stations, the potential savings arent worth risking fuel contamination and expensive repairs. Just hoping the actual repair costs come close to what others have shared here. Really helps having these real experiences to compare against when trying to budget for repairs.