A4 TDI DPF Issues: Black Smoke & Failed Regeneration

I had a very similar issue with my 2011 A6 TDI last year. Having some experience with diesel engines, I recognized the symptoms immediately, especially the black smoke during acceleration and DPF issues. The exhaust back pressure sensor was indeed the root cause. Vehicle diagnostics confirmed this after the engine management light appeared. Initially, I thought it might be a more serious engine performance problem, but the workshop confirmed the sensor failure was preventing proper exhaust flow monitoring. The repair involved replacing the faulty sensor and performing a system reset. Total cost was 245 Euro, including parts and labor. After the fix, the engine management light cleared, smoke disappeared, and the DPF started normal regeneration cycles again. Before suggesting specific solutions, could you share: Current mileage on your A4? Any recent DPF maintenance history? Are you noticing any power loss during acceleration? Have you checked if there are any other vehicle emissions related error codes? This information would help determine if your situation matches what I experienced and whether additional checks might be needed.

Thanks for sharing your experience. My A4 has 66784 KM and the last service was 3 months ago. The pressure sensor reading matches your symptoms exactly, especially regarding the DPF behavior. During acceleration, power loss is minimal but noticeable around 2000-2500 RPM. The auto repair estimate I got seems higher than your repair costs, quoting 450 Euro for the exhaust sensor replacement. Since the vehicle emissions system appears intact otherwise, I think focusing on the back pressure sensor makes sense before exploring costlier repairs. Would you recommend getting a second diagnostic opinion before proceeding with the repair?

Good to hear back from you, and thanks for those details. Your symptoms match my experience even closer than I initially thought, that power loss around 2000-2500 RPM was exactly what I experienced with my A6 before the repair. That 450 Euro quote does seem steep compared to what I paid. The pressure sensor itself should cost around 180-220 Euro, so labor charges appear inflated. With your relatively low mileage and recent service history, I would definitely recommend getting a second diagnostic opinion before proceeding. One thing I learned from my repair, make sure they perform a complete exhaust system pressure test after installing the new sensor. In my case, the technician caught a minor exhaust leak during this test that could have caused the new sensor to fail prematurely. The engine performance returned to normal immediately after my repair. Since your symptoms are so similar, particularly the DPF regeneration issues and black smoke, I expect you will see the same improvement once the faulty sensor is replaced. Consider asking the second workshop specifically about: Their diagnostic process for emission control components, Whether they include post-repair system testing, A breakdown of parts versus labor costs

Given the data from someone who experienced nearly identical issues, I feel more confident about the repair direction. I want to share my decision process here in case others encounter similar problems with their car maintenance needs. My vehicle emissions symptoms line up perfectly with the discussed sensor failure, especially that specific power loss range and DPF behavior. After checking several auto repair shops, I found one that offers similar services for 380 Euro, which seems more reasonable than my initial quote. The shop I chose performs complete exhaust system testing as part of their service package. They will verify the emission control components thoroughly, which should prevent any potential issues with the new sensor installation. The technician also mentioned they would do a full system check to ensure no other exhaust system components are contributing to the problem. This comprehensive approach, combined with the lower cost, makes more sense than rushing into the more expensive repair option. I will proceed with the sensor replacement next week and update this thread with the results. Thanks for helping me avoid potentially unnecessary repairs and saving some money in the process.