Audi Q7 No-Start: Cranks But Won't Fire Up

Had a similar issue with my 2009 Audi Q5 3.2 FSI last winter. Have some experience with basic car maintenance and troubleshooting engine issues. The symptoms were identical, engine cranking but not starting, with check engine light briefly appearing. After a frustrating day of attempted starts, I took it to my regular workshop. The issue turned out to be corroded battery terminals causing intermittent connection problems. Even though the battery itself tested fine, the poor connections were preventing proper power delivery to the ECU and engine management systems. The fix was straightforward: cleaning and tightening all battery connections, plus replacing some worn cable ends. Total cost was 155 Euro including labor. Since then, no engine stalling or starting issues. Before suggesting this is definitely your problem, it would help to know: Any signs of corrosion around battery terminals? Does the engine crank strongly or weakly? Have you noticed dimming lights when trying to start? Any recent work done on the electrical system? Do you have access to a multimeter to test voltage at the battery terminals while cranking? With those details, we might be able to confirm if your Q7 has the same issue or needs different troubleshooting steps.

Last serviced at 14523KM with all routine maintenance completed. Our initial diagnosis pointed to potential ECU failure or fuel injection issues. The workshop did a complete fuel system diagnostic but found no faults. Would be useful to know if anyone else had similar no-start conditions that ended up being engine software related. Getting concerned this might need dealer-level diagnostics to properly identify the root cause of the engine fault. After reading your experience, I will definitely check the battery connections more thoroughly, even though my battery tests good. The check engine behavior you described matches exactly what I am seeing.

Thanks for the additional details about your recent service and diagnostics. After my experience with the battery connection issue, I learned that an engine fault can often be traced back to electrical problems, even when the initial symptoms suggest fuel or ECU issues. Since your Q7 symptoms match what I experienced, especially that specific check engine light behavior during cranking, I strongly suspect an electrical connection problem. When my Q5 had this issue, the workshop found that even with a good battery, voltage drops during cranking were causing the ECU to reset, preventing proper engine start. A few specific checks worth doing: Test voltage at battery terminals during cranking, Clean and inspect all ground straps, especially engine to chassis, Check fuse box connections for any signs of corrosion, Verify ECU connector pins are clean and fully seated My engine surge issues completely resolved after addressing these electrical points, without needing expensive ECU diagnostics or replacement. The intermittent nature of these problems often makes basic scanners show no codes, just like in your case. If these checks reveal nothing, then dealer-level diagnostics might be needed, but start with the electrical system first. It could save you significant diagnostic costs.

Thanks for sharing those insights about the electrical system checks. After inspecting everything you suggested, I found significant corrosion on one of the main ground straps connecting the engine to the chassis, it was almost completely eaten through. The check engine light behavior during my attempts to start makes much more sense now. Going to replace the ground strap and thoroughly clean all electrical connections before moving forward with more complex engine software or fuel injection diagnostics. The similarity between our cases and the way the ECU behaves during cranking strongly suggests this could be the root cause. Will post an update once I replace the ground strap and clean all connections. If that doesnt resolve the engine stalling issue, I might need that dealer-level diagnostic after all. Really hoping this electrical fix works like it did in your case.