Audi Q7 Hybrid: Rough Running + Exhaust Leak Warning

As someone with a good amount of car repair experience, I dealt with very similar symptoms on my 2016 Audi Q5 Hybrid last year. The engine light came on along with rough running and exhaust issues. After diagnosis, it turned out to be a faulty Lambda sensor, which was causing incorrect fuel mixture readings and affecting the exhaust treatment system. The repair took about 4 hours and cost 375 Euro including parts and labor. The symptoms cleared up completely after replacement, and the engine light has stayed off since then. In your case, while the symptoms sound similar, several components could be causing this, including: Lambda sensor, EGR valve malfunction, Exhaust leak at connection points, Particulate filter issues, NOx sensor failure To help narrow it down, could you share: Any diagnostic codes if you have them, When exactly the symptoms started, Whether the engine light is solid or flashing, If fuel consumption has increased, Whether the symptoms are worse when the engine is cold or warm These details would help identify if your issue matches what I experienced or if it might be something different.

Thanks for the detailed response. Following up on my case, I took the car to an authorized service center last week at 9710 KM. The diagnostic revealed that the particulate filter was indeed clogged, but they also found a crack in the exhaust pipe near the catalytic converter connection point. The DEF fluid level was also critically low, which contributed to the emission system issues. The repair costs ended up being higher than expected at 890 Euro. The good news is that after replacing the damaged exhaust components and topping up the DEF fluid, the engine light cleared and the rough running has completely stopped. No more exhaust smell either. Would it be worth checking these components more frequently to prevent similar issues in the future?

Glad to hear you got it sorted. Your repair experience actually sounds similar to what happened with my Audi later on. A few months after my initial Lambda sensor repair, I also discovered a crack near the catalytic converter connection point during routine maintenance. Regular checks are definitely worth it. Since that incident, I maintain a strict monitoring schedule: DEF fluid levels checked every 10000km, Visual inspection of exhaust components, especially connection points, every 6 months, Particulate filter status monitored through the onboard computer, NOx sensors performance checked during regular service intervals This preventive approach has helped catch potential issues before they become major problems. The exhaust leak repair is particularly important since it can affect multiple systems and cause the engine light to trigger due to incorrect readings. Based on both our experiences with these Audis, keeping the DEF fluid at proper levels and monitoring exhaust system integrity seems crucial for preventing emission-related problems. The repair cost you mentioned is in line with what these fixes typically run, especially considering multiple components needed attention.

Thank you for sharing those maintenance intervals. This is really helpful for my situation. After my repair experience, I invested in an OBD2 scanner to keep track of the engine light codes and monitor the NOx sensors myself between services. The exhaust pipe seems to be holding up well after the repair, and I am being extra careful to check the DEF fluid level monthly now. The particulate filter readings are also staying within normal range according to the scanner. Good point about the connection points, I will make sure to have those inspected regularly. The 890 Euro repair bill was tough to swallow, but it is still cheaper than letting these issues cascade into bigger problems. Right now the car runs perfectly, and I plan to stick to this more proactive maintenance approach to avoid similar issues down the road. One last question, would the scanner readings be reliable enough to catch potential problems early, or should I still get regular professional diagnostics done?