Q2 Diesel Glow Plug Issues Cause Smoke and Warning Lights

Had similar symptoms with a 2014 Audi Q3 2.0 TDI. The ignition system was showing identical warning signs, constant preheating lamp and check engine light. The smoke during acceleration is a clear indicator of problems with the heating module. The root cause was a damaged wiring harness connecting to the preheating unit, combined with corroded plug connections. The vehicle heater system requires proper electrical contact to function correctly. When these connections fail, it causes incomplete fuel combustion, leading to the smoke. This is a serious issue that needs immediate attention. Continuing to drive can lead to: Further damage to the engine preheating system, Increased fuel consumption, Potential engine performance issues, Risk of complete preheating failure The repair involved: Full diagnostic scan, Removal of preheating unit, Replacement of damaged wiring, Installation of new plug connectors, System reset and testing Safe to drive short distances to the repair shop, but not recommended for regular use until fixed. The preheating system is crucial for proper diesel engine operation, especially during cold starts.

Thanks for sharing your experience. Same thing happened with my Audi Q2. The car preheater system showed identical issues and the electrical fault triggered both warning lights. The mechanic told me it was indeed the preheating unit that needed replacement. Did you track how much the complete repair ended up costing? Also wondering if youve had any other electrical issues since getting it fixed. Would help to know if I should expect any related problems down the line.

The control unit repair for my Q3 was straightforward and cost effective at 95 Euro, mainly fixing faulty cable connections to the preheating unit. Since getting the electrical fault resolved, the car runs perfectly with no preheater problems or related issues. The repair shop found a defective part in the wiring system which was causing poor connections to the preheating control unit. The smoke issue cleared up immediately after the fix, and both warning lights turned off as soon as the system was reset. The key was catching it early before it could damage other components of the preheating system. Going on 8 months now with no electrical problems or preheating unit concerns. Regular maintenance and keeping the connections clean should prevent similar issues from developing again.

I went to the mechanic last week to fix the issue. The vehicle heater problem was exactly as described, faulty wiring in the control unit. Total repair came to 320 Euro, more than expected since they found additional wear in the heating module that needed attention. The repair took about 4 hours. They replaced the defective part, rewired the connections, and performed a full system diagnostic. No more smoke from the exhaust and both warning lights are now off. The car starts perfectly even in cold weather. Good call on pointing out the wiring issue. Just glad I caught it before causing more extensive damage to the engine. Thanks again for the helpful advice.