VW Lupo Diesel Stalling: Fuel System Woes Explained

Had a similar issue with my 2006 VW Polo diesel. As someone with moderate experience working on diesel engines, I can tell you fuel system problems can be tricky to diagnose. The symptoms you describe match what I experienced, engine stalling at idle and check engine light. Initially thought it was bad fuel quality, but it turned out the fuel filter connection had a loose electrical plug that was causing intermittent fuel supply issues. Took it to a workshop where they diagnosed the exact issue, a faulty cable connection to the fuel system component. The repair cost was 95€ including diagnostics and fixing the connection. Since then, no more stalling or warning lights. Before jumping to conclusions about fuel quality, would be helpful to know: What error codes are you getting specifically? Have you noticed any engine knock? When was your last fuel filter change? Does the problem occur more when the engine is cold or warm? With these details, it would be easier to determine if your issue matches what I experienced or if it might be something else in the fuel system.

Thanks for sharing the details. My last service was 4 months ago at 109554km. The error codes I am getting are P0190 and P0087, both related to fuel rail pressure. The stalling happens more frequently when the engine is warm, and I notice a slight engine knock when accelerating. The fuel filter was changed during the last service, which makes me think the combustion chamber might be getting inconsistent fuel supply. Since your Polo had similar symptoms with the loose connection, I will check all fuel system connectors first. The intermittent nature of the problem does sound similar to what you experienced. Hoping its just a connection issue rather than a major fuel system component failure, as those repairs tend to be much costlier than 95€.

Thanks for those additional details. The error codes P0190 and P0087 definitely point to fuel pressure issues, similar to what I experienced. However, the engine knock during acceleration combined with warm-engine stalling suggests this might be slightly different from my connector problem. In my case, I initially overlooked a critical detail, the connection issue was causing inconsistent readings in the fuel pressure sensor, but I never experienced engine knock. Your situation with knock and warm-engine stalling hints at possible fuel contamination affecting the combustion chamber performance. While checking connections is a good first step, I recommend also: 1. Taking a fuel sample from your tank to check for contamination 2. Inspecting the fuel rail pressure sensor itself 3. Testing the high-pressure fuel pump operation When my Polo had the loose connection fixed, the symptoms cleared up immediately. If checking connections doesnt resolve your issue, the fuel pressure pump might need attention. The warm-engine stalling typically indicates a component that fails as temperatures rise. My total repair ended up being simple, but based on your symptoms, you might want to prepare for a more involved fuel system diagnosis. Modern diesel injection systems are sensitive to both fuel quality and pressure variations.

Great advice about the fuel rail pressure! Your diagnosis of the P0190 and P0087 codes makes sense. The timing of the stalling when the engine is warm definitely suggests something different from a simple loose connection. I checked all the connectors this morning and they seem secure. Given the fuel system symptoms persist, I will follow your suggestion and have the fuel tested for contamination first. The engine knock during acceleration is concerning, especially since its a recent development that coincides with the warm stalling issue. Since my last fuel filter change was so recent, I suspect either fuel contamination or the high-pressure fuel pump could be failing. The inconsistent fuel rail pressure would explain both the stalling and knocking symptoms. Going to take it to the shop tomorrow and request they specifically check these components. Will update once I know more about the fuel quality test results and pressure pump diagnosis. Really hoping to avoid major fuel system repairs, but at least now I have a clearer picture of what to investigate. Thanks for helping narrow down the potential causes.