Q7 Power Loss and Rough Running: Bad Injector Alert

Having some experience with engine management issues, I faced nearly identical symptoms with my 2015 Audi Q5. The check engine light came on, and I noticed similar problems with rough running and excessive fuel consumption. After monitoring the air-fuel ratio, my workshop confirmed a faulty fuel injector was causing a rich mixture. The defective injector was spraying too much fuel, leading to poor fuel economy and the jerking sensation during acceleration. The repair involved: Complete diagnostic scan, Fuel injector testing, Replacement of one faulty injector, System reset and adaptation Total cost was 515 Euro for parts and labor, but it completely resolved the issues. The engine now runs smoothly with normal fuel consumption. Before suggesting specific solutions, could you share: Current mileage on your Q7? When was the last time spark plugs were replaced? Have you noticed any unusual exhaust smell? Did the problem start suddenly or develop gradually? This information would help determine if your case matches what I experienced with the injector failure.

Thanks for sharing that detailed case. My Q7 has 102823 KM and the last major service was done 6 months ago which included a full set of new spark plugs. Since you mentioned injector issues, the symptoms do sound very similar. My rich mixture problem appeared quite suddenly, within a day or two. The check engine light came on during a regular drive. There is a strong fuel smell from the exhaust, especially when idling. The fuel consumption increased from around 11L/100km to nearly 15L/100km. The catalytic converter also seems to be running hotter than usual based on the exhaust temperature readings from my OBD scanner. Has anyone else had experience with injector testing costs at specialist workshops? The dealer quoted 800 Euro just for diagnostics which seems excessive.

From my previous experience with the Q5 injector issue, those symptoms match exactly what you're describing, especially the sudden onset and strong fuel smell. The increased fuel consumption from 11L to 15L/100km is also very close to what I experienced when my injector failed. For testing costs, 800 Euro at the dealer is definitely on the high side. After my repair, I found several independent workshops that specialize in fuel injection systems and offer comprehensive injector testing for around 200-300 Euro. The testing usually includes: Pressure flow testing, Spray pattern analysis, Electronic response checks, Back-leakage measurement The high exhaust temperature you mentioned from the OBD readings is another classic sign of a rich mixture caused by faulty fuel injectors. This excess fuel can damage your oxygen sensor and catalytic converter if left unchecked for too long. Based on your symptoms matching my case so closely, and given that your spark plugs are new, I strongly suspect one or more injectors are the culprit. The fact that its running rich across different load conditions suggests its not an oxygen sensor issue, which typically causes problems at specific RPM ranges. A full diagnostic at a fuel system specialist should pinpoint exactly which injector is causing the rich mixture. They can often clean and test the injectors first before recommending replacement.

Thanks everyone for the helpful replies and cost guidance. Based on the shared experiences, I feel more confident now that my Q7 is likely suffering from a faulty injector rather than an oxygen sensor issue. The symptoms match too closely to be coincidence, especially the sudden onset, rich mixture, and specific increase in fuel consumption. I found a specialized fuel injection workshop that quoted 250 Euro for complete injector testing and diagnosis. Much more reasonable than the dealer price. Will book it in next week and have them check the spray patterns and flow rates. The strong fuel smell and high exhaust temperatures are concerning, so better to get it sorted quickly before it affects other components. Really hoping its just one bad injector like in your Q5 case and not a full set replacement. Will update the forum once I get the test results and know the exact cause of the check engine light and rich mixture problems. The catalytic converter temperature readings from my OBD make me a bit nervous about potential damage from running too rich for too long.