VW Lupo's Black Smoke Points to DPF Trouble

Had similar issues with my VW Polo TDI (2003, similar mileage) last season. The symptoms match exactly what you describe, drop in power and black exhaust smoke are classic signs of DPF problems affecting engine backpressure. Started with the check engine light, followed by reduced fuel efficiency and that characteristic dark smoke. The garage diagnostic confirmed the diesel filter was about 90% clogged. A simple cleaning would not resolve it since the filter had microscopic cracks from long-term heat stress. The complete diesel filter replacement was necessary in my case. This is a serious repair that requires proper diagnostic equipment and expertise. The exhaust system needed to be partially dismantled to access and replace the DPF unit. Before going to a shop, check if the engine management light shows specific DPF-related error codes. Consider that even temporary DPF issues can quickly escalate to permanent damage if not addressed. The reduced performance you notice is the engine protecting itself from potential damage due to increased backpressure. Delaying the repair typically leads to more extensive exhaust system damage, so getting it properly diagnosed soon is important. Regular highway driving at consistent speeds might temporarily improve symptoms but won't fix the underlying issue.

Thanks for sharing your experience. The symptoms you described with your Polo match my Lupo situation perfectly. Did you remember roughly how much the complete diesel filter replacement ended up costing? My vehicle inspection is coming up soon and I want to budget properly. Also curious if youve had any regeneration issues or similar problems since the repair? My fuel efficiency has gotten really bad lately so I want to make sure fixing the DPF will actually solve the underlying problem.

Since replacing the defective diesel particulate filter on my Polo, all those worrying symptoms completely cleared up. The repair job came to 1550€, which included the new DPF unit and labor costs for the complete filter replacement. While it was a significant expense, the improvement in performance made it worthwhile. The engine runs smoothly now with no backpressure issues or regeneration problems. Fuel consumption returned to normal levels right after the repair. The engine light stayed off and the dark smoke disappeared completely. The garage did a thorough job diagnosing and fixing the root cause of the DPF clogging. Based on my experience, once you get the proper diesel filter replacement done, these problems should not return as long as you maintain regular highway driving cycles. The investment in fixing a defective DPF pays off through restored performance and prevented future damage to the exhaust system.

Thanks for the helpful advice. I finally took my Lupo to a certified diesel specialist last week. The sensor fault scan confirmed heavy DPF clogging just as suspected. Got quoted 1400€ for the complete filter replacement, which was actually less than I feared after researching typical repair costs. The mechanic did a thorough inspection and found the old DPF was completely blocked, explaining the terrible fuel efficiency lately. They completed the work in two days, replaced the diesel filter and cleaned the entire exhaust system. What a difference it made, the engine runs like new again with no more dark smoke or sluggish acceleration. Fuel consumption improved dramatically and the backpressure readings are now perfect according to their final test report. Really glad I got it fixed properly instead of trying cheaper temporary solutions. The investment was worth it to restore proper performance and avoid bigger problems down the road. Will definitely keep up with regular highway drives to prevent future DPF issues.