VW Polo DPF Warning: Smoke & Power Loss Alert

Had a similar issue with my 2017 VW Golf TDI. Have some experience working with diesel engines and their typical exhaust system problems. The symptoms you describe match exactly what I encountered, reduced power, warning lights, and dark smoke from the diesel exhaust. After multiple attempts at DPF regeneration failed, the workshop diagnosed a faulty exhaust back pressure sensor. This sensor is crucial for proper particulate filter operation and engine performance. The repair involved replacing the defective sensor and performing a system reset, costing 245€ in total. Since the fix, the exhaust system has been working perfectly with no more warning lights or power issues. To provide more specific advice about your case, could you share: Current mileage on your Polo, Which warning lights are showing exactly, Whether you do mostly city or highway driving, If you noticed the issue suddenly or it developed gradually, Any previous particulate filter or exhaust system repairs These details would help determine if your issue is identical to what I experienced or might need a different approach.

Thanks for your helpful reply. At 44197km, my Polo is still relatively low mileage. The warning light pattern matches exactly what you described, and like your case, the issue came on quite suddenly during city driving. I have never had any previous repairs related to the particulate filter or exhaust system since my last service. The DPF issues you mentioned with the pressure sensor malfunction sound very similar to what Im experiencing. Good to know the repair costs were reasonable in your case. Im scheduling a workshop visit next week to have them check the exhaust back pressure readings and sensor functionality.

Thanks for providing those details. The mileage and driving pattern on your Polo align perfectly with when I encountered the pressure sensor issue on my Golf. The sudden onset during city driving is particularly telling, low speed urban cycles often prevent proper regeneration of the diesel particulate filter, leading to pressure sensor misreadings. Before my sensor replacement, I tried several highway runs to force regeneration, but like yours, the emission control system remained problematic. After the exhaust back pressure sensor replacement, I also had them perform a full diagnostic reset of the exhaust system. This combination resolved both the reduced engine power and the dark smoke issues completely. The repair has held up well for over 25000km now with no recurring problems. When you visit the workshop, have them specifically check the wiring connection to the pressure sensor too. In some cases, the connector can deteriorate from exhaust heat, causing similar symptoms without needing a full sensor replacement. Could save you some money if thats the case. Would be interested to hear what they find during your service visit, as these diesel engine issues can sometimes be tricky to diagnose correctly on the first try.

Thanks for all the detailed feedback about the sensor issues. You really helped clarify what I should expect at the workshop visit. The exhaust back pressure sensor seems to be the likely culprit, especially since my symptoms match your experience so closely. The tip about checking the wiring connections first is particularly useful, I will definitely mention this to the technician to potentially save on unnecessary parts replacement. Since my diesel particulate filter has never needed work before, and the emission control problems came on suddenly during city driving just like in your case, I am fairly confident we are dealing with the same root cause. I will update the forum after my workshop visit next week with what they find and the actual repair costs. Hopefully the DPF regeneration and sensor checks will confirm the diagnosis and lead to a straightforward fix like you experienced with your Golf. Really appreciate you taking the time to share your experience in such detail.