Q7 Diesel Glow Plug Warning Light Stays On Permanently

Recently dealt with similar glow plug issues on my 2013 Audi A6 3.0 TDI. The continuous preheat indicator often indicates a failed glow plug or its control module. During cold starts, the engine would run rough for the first minute, and fuel efficiency dropped noticeably. The check engine light came on intermittently. Diagnosis revealed two failed glow plugs and a deteriorating control module. The repair required replacing all six glow plugs as a set, plus the control module. This was not just a minor fix, the entire intake manifold needed removal to access the plugs properly. A failed glow plug can cause engine misfire and poor engine combustion if left unattended. The job took about 6 hours at the shop. While this is a significant repair, its not catastrophic to the engine if addressed promptly. Worth noting that glow plug issues are common in diesel engines around the 50000km mark. To prevent future issues, regular diesel engine maintenance and using high-quality fuel helps extend glow plug life. The repair resolved all cold start issues and restored normal operation.

Thanks for sharing that experience. I had almost identical symptoms on my Q7, the preheat light staying on and rough cold starts. Ended up being just two faulty glow plugs in my case, but the labor was still extensive since they had to remove quite a bit to access them. Would you mind sharing what the total repair cost was in your case? Always helpful to know what others paid. Also curious if you have had any diesel engine issues since the repair? My check engine light has stayed off for 6 months now but I still monitor cold starts carefully.

After getting the glow plug issue resolved by my mechanic for 440 Euro, everything has been running perfectly. The repair included replacing two defective glow plugs and running a full diagnostic check. Since the fix, cold starts are smooth with no engine misfire issues, and the check engine light has stayed off completely. The fix was actually less expensive than I initially expected, since only two glow plugs needed replacement rather than the full set. Most importantly, the preheat indicator now works normally, only lighting up briefly during startup as it should. For the last 8 months since the repair, the engine has been performing flawlessly with no diesel-related problems. Regular maintenance and quality fuel definitely help prevent these issues from recurring. The investment was worth it to avoid potential long-term engine damage from faulty glow plugs. Your experience with monitoring cold starts is smart, its a good way to catch any potential issues early before they become major problems.

I definitely appreciate all the feedback shared here. After dreading another potential bad mechanic experience, I finally took my Q7 to a different shop last week. The diagnosis confirmed exactly what was discussed, two faulty glow plugs needed replacement. The total came to 520 Euro including parts and labor. While not cheap, the new mechanic was transparent about the work needed and explained everything clearly. The job took about 5 hours since they had to remove several components to access the glow plugs. Since the repair, my diesel car starts perfectly even on cold mornings. The persistent preheat indicator issue is completely resolved and fuel efficiency has actually improved slightly. More importantly, the rough idle during cold starts is gone. I also had them do a full system scan which showed no other engine light codes stored. The mechanic recommended checking the glow plugs again at 100000km as preventive maintenance. For now, Im just glad to have this sorted with a shop I can trust.