VW Polo Diesel Injection Issues & Common Fixes

I had nearly identical issues with my 2002 VW Golf TDI. Having some experience with diesel engines, those symptoms immediately made me think of injection problems. My vehicle showed the same issues, rough idle, poor starting, significant power loss, and the engine would misfire under load. The fuel consumption increased by about 20%. The workshop first performed a diagnostic scan and then did an injection pressure test which confirmed dirty injection valves were causing improper fuel atomization. They cleaned the complete injection system and replaced one particularly problematic valve. The repair took about 4 hours and cost 515€ total, including parts and labor. The vehicle has been running perfectly since the repair, smooth idle, proper power delivery, and normal fuel consumption returned. To provide more specific advice about your case, could you share: Current mileage on your Polo, When was the last fuel filter change, What type of diesel fuel you typically use, Whether any warning lights are illuminated, If the problems started gradually or suddenly This information would help determine if your issues are similar to what I experienced with my Golf and whether the repair approach might be comparable.

Just had my latest service last month. During cold starts, I can definitely hear knocking sounds that werent there before, and the repair shop confirmed uneven fuel spray patterns during their pressure test. My experience matches what you described, the vehicle struggles with performance and has developed a noticeable misfire under acceleration. Even with premium diesel fuel, the consumption has increased dramatically. The problems appeared quite suddenly after a long highway drive. The warning light for glow plugs occasionally flashes now, which it never did before. Getting it properly diagnosed next week, but your repair costs sound reasonable if it turns out to be the same injection system issue.

Thanks for the additional details. That knocking during cold starts combined with the spray pattern test results definitely confirms our suspicion of injection system problems, almost identical to what I experienced with my Golf. The glow plug warning is particularly telling. In my case, the clogging in the injection system was causing irregular combustion, which triggered similar warning signals. The uneven fuel delivery puts extra stress on the glow plugs and can trigger false warnings. Quick tip from my experience: Before your workshop visit, try running a tank of high-quality diesel with a proper cleaning additive. While it likely wont fix the underlying issue, it helped minimize further performance degradation in my case while waiting for the repair appointment. My vehicle showed immediate improvement after the injection system service. The cold start knocking disappeared completely, and normal engine performance returned within about 100km of driving as the system fully cleared out. Based on your description and my identical experience, you should expect a similar repair scope and cost range to what I had. The diesel injection cleaning and potential replacement of problematic nozzles typically runs 450-600€ depending on how many components need replacement. Would be interested to hear what your workshop finds during the diagnostic appointment.

Thank you for sharing those details about your repair experience. The service history is certainly helpful, and those symptoms you describe, especially the cold start knocking and uneven fuel spray patterns, strongly suggest injection system problems. After hearing about your specific issues, I am even more convinced our vehicles suffered from the same problem. The glow plug warning is definitely concerning, but at least now I know it could be related to the irregular combustion caused by faulty injectors rather than an additional problem. That saves me some worry about potentially larger issues. I appreciate the tip about using the fuel additive before the service appointment. I will pick some up today since I need to refill anyway. Even if it just helps prevent things from getting worse before the repair, that seems worthwhile. The repair cost estimate gives me a good baseline for what to expect. The emissions and engine performance issues are becoming unbearable, so I will certainly proceed with the repair if the diagnostic confirms the diesel injection system needs service. The misfire under load is particularly problematic during my daily commute. I will update this thread once I get the final diagnosis and repair completed next week. The information you provided has been extremely helpful in understanding what I am likely dealing with.