VW Tiguan Glow Plug Failure Causing Smoke & Warning Lights

Had similar issues with my 2010 VW Touareg TDI. The constant preheating lamp and engine light pointed to an electrical fault in the preheating system. After inspection, the problem was traced to damaged wiring connections at the car preheater unit. The smoke during acceleration is a typical symptom when the engine preheat system fails to properly warm the combustion chamber. This causes incomplete fuel burning, especially noticeable in diesel engines. The fix required replacing several corroded plug connections and a defective part in the glow plug control module. Not a catastrophic repair, but definitely something that needs prompt attention to prevent engine performance issues and potential damage to other components. These preheating unit problems are fairly common on VW TDI engines from that generation when they reach around 100000km. The repair process mainly involves diagnostic testing to pinpoint the exact electrical fault, then replacing the compromised connections or control module if needed. Most shops familiar with VW diesels should be able to diagnose and repair this issue. Would strongly recommend having it checked soon, as continued driving with faulty preheating can lead to starting problems and reduced engine performance.

Thanks for sharing your experience with the Touareg heating module repair. My Tiguan had these exact symptoms last winter and getting it fixed made a huge difference. The preheating system has worked flawlessly since the repair. Could you share how much the fix cost in your case? Also wondering if you have had any other ignition system issues pop up since getting those electrical faults sorted out? My vehicle heater still works great but curious if I should watch for any related problems down the line.

Great to hear your Tiguan is running better now. In my case with the Touareg, the control unit defective status was resolved last month. The repair focused on fixing faulty cable connections in the preheating system, total cost came to 95€. Since getting the electrical fault corrected, the vehicle heater and ignition system have performed perfectly. No smoke issues, no warning lights, and starts smoothly even in cold conditions. The car electronics are all functioning as they should. A proper fix of the preheating control unit typically resolves the issue completely. The key was catching it early before it could affect other engine components. Based on my experience, once the defective part is properly repaired, you likely won't face related problems, these systems are quite reliable when maintained correctly. Just keep up with regular maintenance and you should be fine. The preheating system is designed to last, and fixing the root cause rather than just treating symptoms usually prevents future complications.

Thanks everyone for the helpful replies. I took my Tiguan to a specialized workshop last week and they confirmed the preheating unit had failed. The heating module needed replacement along with some worn wiring. Total repair came to 620€ including parts and labor. The mechanic showed me the corroded control unit and explained how the electrical fault had developed over time. Since the repair, the car starts perfectly and the exhaust smoke is completely gone. No more warning lights on the dash either. Really glad I got this fixed before winter. The specialist did a proper job diagnosing the defective part and I finally found a mechanic I can trust.