Audi S6 DPF Issues: Black Smoke and Power Loss Alert

I faced similar issues with my 2018 Audi A6 diesel. My experience with diesel engines is moderate, having owned several over the past few years. The symptoms you describe match exactly what I encountered, reduced power, warning lights, and emission control problems. The workshop diagnosed a faulty exhaust back pressure sensor, which was causing incorrect readings and affecting the particulate filter operation. The repair involved replacing the pressure sensor and performing a system reset. Total cost was 245 Euro, including parts and labor. The fix resolved all symptoms immediately, no more black smoke, proper power restored, and all warning lights cleared. Before jumping to conclusions about the particulate filter itself, which can be much more expensive to replace, its worth checking the sensor first. To provide more specific guidance, could you share: Current mileage, Any recent maintenance history, Exact error codes from your diagnostic scan, Whether symptoms appear more during cold starts or after the engine is warm This information would help determine if your issue matches what I experienced or might be something different in the emission control system.

Had the same issue at 149696 KM. The reduced power and diesel exhaust problems were exactly as you described. After multiple diagnostic tests, it turned out the DPF issues were caused by a combination of blocked exhaust system sensors and carbon buildup. The fix involved cleaning the entire exhaust system and replacing two faulty sensors. The diesel engine returned to full power immediately after the repair. Cost was around 650 Euro for the complete service, which also included a software update to the engine management system. Would recommend getting the diagnostic codes checked again, focusing specifically on the DPF pressure readings when the engine is both cold and at operating temperature. This helped pinpoint the exact problem in my case.

A quick update on the DPF pressure sensor issue we discussed earlier: After running my A6 for another few months following the sensor replacement, I noticed the problem starting to return. Black smoke and reduced power appeared again, but this time the workshop found significant carbon buildup behind the particulate filter. The low pressure readings were actually a symptom of a more extensive exhaust system blockage. Ended up needing a complete DPF cleaning service plus replacement of the exhaust pressure sensor again. Total cost this time was 850 Euro, but the diesel engine has been running perfectly since. Worth mentioning that regular highway driving helps prevent these DPF issues by allowing proper regeneration cycles. The first repair only addressed the sensor, but the underlying carbon deposits were the real culprit causing the pressure problems. Based on your experience, it sounds like your workshop caught both issues at once, which saved you from having to make multiple repairs like I did. The combined sensor replacement and cleaning approach seems to be the most effective solution for these particular diesel engine symptoms.

Thanks for sharing those details about the sensor and carbon buildup issues. My Audi S6 is currently at 152000 KM and I had the full diagnostic scan done yesterday. The error codes specifically point to low DPF pressure readings, matching what you experienced. The workshop has booked it in for next week. Based on your feedback, I will ask them to check both the pressure sensors and examine the particulate filter for carbon deposits. Makes sense to address both potential issues at once rather than risk having to go back for additional repairs. The emission control problems are definitely worse during cold starts, with the black smoke more noticeable first thing in the morning. The exhaust system definitely needs a thorough inspection. Will update once the repairs are complete, but your experience helps confirm I am on the right track with the diagnosis. Good point about regular highway driving. Since most of my trips are short urban runs, this could explain why the DPF is struggling to complete proper regeneration cycles.