Audi A4's EGR Valve Nightmare: Smoke and Power Loss

I had a very similar issue with my 2021 Audi A4 diesel last winter. With some automotive repair experience, I can definitely relate to these symptoms, especially the rough idle and power loss issues. The symptoms you describe strongly suggest an EGR valve problem, which perfectly matches what I experienced. My car also had that distinctive hissing sound during acceleration and poor emissions performance. After diagnosing a vacuum leak and running an emissions test, my workshop confirmed it was indeed a jammed EGR valve. The repair involved cleaning the entire EGR system and replacing the faulty valve. Total cost came to 355 Euro, including parts and labor. The catalytic converter was also inspected to ensure no related damage occurred. Since the repair, fuel economy returned to normal and all performance issues disappeared. These EGR problems can get worse if left unattended, potentially leading to more expensive repairs. Could you share: Current mileage on your A4? When did symptoms first appear? Any recent maintenance history? Which engine variant specifically? This information would help determine if your case is similar and whether the repair approach that worked for me would be suitable for your situation.

Just had my latest service at 186372 KM and can confirm your diagnosis matches my symptoms exactly. The EGR valve recirculation system was indeed the culprit in my case. After thorough cleaning and valve replacement, the rough idle completely disappeared and my diesel engine performance returned to normal. Repair costs totaled 420 Euro at an independent specialist. The fix lasted about 6 hours since they had to remove several components to access and properly clean the entire system. The vehicle emissions test after repair showed everything back within spec. Worth noting that my repair also included replacing some cracked vacuum lines they discovered during inspection, which were contributing to the hissing sound.

Thanks for the feedback on your A4 repair. Good to hear the EGR valve replacement resolved your issues. The difference in repair costs between our cases likely comes from those additional vacuum line replacements you needed. My A4 has now run perfectly for about 15000 km since the EGR repair, with no check engine lights or performance issues. Fuel consumption stays consistently normal and the emissions remain clean. The hissing and jerking during acceleration never returned. One tip from my experience: I now use a higher grade diesel fuel and changed to shorter service intervals for the EGR system to prevent future clogs. The repair shop suggested this could help maintain proper emissions control and extend the life of the new valve. For others reading with similar symptoms in their diesel engines: the repair costs can vary based on labor rates and whether additional components need replacement. The key is addressing EGR issues promptly before they cause more extensive damage to the emissions system. Would be interested to hear how your fuel consumption numbers look now compared to before the repair. Mine improved by about 15% after fixing the EGR valve.

Thanks for sharing those valuable details about your A4 repair experience. The EGR valve repair on my A4 has made a huge difference in performance. My fuel consumption improved by around 20%, even better than your results. Currently getting about 6.8L/100km on highway runs. Just passed another emissions test last week with excellent readings. The rough idle is completely gone and acceleration is smooth again with no hissing or jerking. Following your advice about premium diesel fuel and more frequent EGR system maintenance checks. My mechanic suggested the same preventive approach. Good point about varying repair costs. While my bill was higher at 420 Euro due to the vacuum leak repairs, it was worth every cent considering the improved performance and peace of mind. For anyone else dealing with similar symptoms, getting a proper diagnosis and fixing EGR issues promptly definitely helps avoid bigger problems down the road. The thorough cleaning of the entire system rather than just replacing parts seems to have been key to resolving all the issues. Will definitely stick to the enhanced maintenance schedule to protect this investment.