VW Polo Diesel Performance Issues: EGR Valve Alert

Had a very similar issue with my 2015 VW Golf diesel. The symptoms you describe match exactly what I experienced, reduced power, black smoke, and that characteristic hissing sound pointing to a vacuum leak around the EGR valve area. After some initial diagnostic work, the workshop confirmed a faulty EGR valve that was stuck partially open. They advised against just cleaning it given the extent of carbon buildup and complete valve seizure. The full replacement including parts and labor came to 355€, which solved all the issues completely. Since then, the engine runs smoothly with normal fuel consumption and no check engine light. The black smoke disappeared entirely, confirming the exhaust gas recirculation system is now working properly. To provide more specific advice about your case, could you share: Current mileage on your Polo, Whether you notice the issues more during cold starts, If any diagnostic codes have been read, Your typical driving pattern (city/highway mix), When you last had a major service These details would help determine if your case matches the common EGR valve failure pattern in these engines and whether a cleaning attempt might be worth trying before replacement.

Thanks for all the details everyone. My Polo has 19738km on the clock and just had its annual service last month. Started getting these symptoms right after passing the emissions test, which makes the EGR valve theory even more likely. The cold start behavior is definitely worse and the rough idle becomes really noticeable especially in the morning. The vacuum leak sound gets particularly loud under acceleration on cold engine. Interesting to hear about that Golf repair cost. Local shop quoted me 420€ for a complete EGR valve replacement including labor, which seems a bit steep in comparison. Might try cleaning first since the mileage is relatively low, unless others here strongly advise against it for these diesel engines.

Just wanted to follow up on your situation since we had such similar issues. With your mileage being relatively low, I agree that trying an EGR cleaning first makes sense. When my Golf had these problems, the much higher mileage (78000km) was a key factor in going straight for replacement. The cold start symptoms you describe are textbook EGR valve issues. The vacuum leak sound during cold acceleration matches exactly what I experienced before the repair. The timing after your emissions test is also typical, the increased testing cycles can sometimes accelerate carbon buildup or reveal existing EGR problems. That 420€ quote does seem high compared to what I paid. I would suggest getting a second opinion, as EGR valve prices can vary significantly between suppliers. If you decide to try cleaning first, just ensure the workshop does a proper diagnostic check to confirm no other components in the recirculation system are affected. The morning rough idle you mentioned was particularly problematic on my car too, but completely resolved after fixing the EGR. These diesel engines are generally very reliable once the emissions control systems are working correctly. Would be interested to hear how the cleaning attempt works out if you go that route. The success rate really depends on how stuck the valve is and the type of carbon deposits present.

Thanks for the detailed responses and recommendations. After getting a second quote that came in at 380€, I decided to try the EGR cleaning route first since my Polo has such low mileage. Booked it in for next week. The morning symptoms have actually gotten worse this past week, the rough idle is really noticeable and that vacuum leak sound is impossible to miss during cold starts. The catalytic converter also started making unusual noises, which has me a bit worried about potential connected issues in the exhaust system. I will definitely report back on whether the cleaning resolves the problems. If it does not improve the vehicle emissions and performance issues, I will proceed with the complete EGR valve replacement. Really hoping to avoid that higher cost, but also want to prevent any additional damage to the diesel engine from running it too long with these symptoms. Will keep monitoring the cold start behavior and fuel consumption until the service appointment. At least now I know what to expect from the repair process based on your similar experience.