Jetta Diesel Glow Plug Failure Causing Smoke Issues

Had a similar situation with a 2011 VW Passat TDI. The engine preheat system showed identical symptoms, continuous glow plug light and engine warning. The vehicle heater control module turned out to have corroded connections, causing electrical fault signals. The smoke during acceleration typically indicates incomplete combustion due to improper preheating. In my case, the ignition system diagnostic revealed two failed glow plugs and damaged wiring to the control unit. The car electronics were affected by moisture penetration at the main connector. The repair required: Replacing the glow plug control module, Installing new wiring harness for the preheater system, Replacing 3 faulty glow plugs, Cleaning all electrical connections This was classified as a serious issue since it affects cold starting ability and engine performance. If left unfixed, it can lead to starter motor damage and increased fuel consumption. The repair resolved both the continuous warning lights and smoke issues. The symptoms match classic glow plug control unit failure patterns in TDI engines. Recommend getting the car electronics diagnosed with proper diagnostic equipment before replacing individual components.

Thanks for sharing those details about your Passat repair. I am facing nearly identical symptoms with my 2014 Jetta TDI right now, the continuous glow plug light and smoke are really concerning. Your experience with the defective control unit and wiring issues sounds exactly like what I might be dealing with. I am planning to take it to the shop next week for diagnostics. Would you mind sharing how much the total repair cost in your case? Also curious if you have had any recurring issues with the car preheater system since getting it fixed?

After getting my Passat properly diagnosed and repaired, the preheating control unit defective issue was fully resolved. The mechanic found the main problem was indeed a faulty cable connection at the heating module, much simpler than my initial repair. The total cost came to 95€ for fixing the defective part and connections. This was significantly less than expected, as the car electronics diagnosis showed it was just the wiring rather than a complete ignition system failure. The vehicle heater has worked flawlessly since the repair, no more warning lights or smoke issues. The cold starts are smooth now, and the engine performs perfectly. If your Jetta symptoms are similar, having the connections checked first could save you money before replacing major components. Worth mentioning that proper diagnostic testing is essential, sometimes what appears to be a major preheating system failure can be resolved by repairing simple electrical connections.

I finally got my Jetta fixed after dealing with those frustrating glow plug and smoke problems. Took it to a different mechanic who actually knew what they were doing with diesel engines. The heating module diagnosis showed exactly what you mentioned, corroded wiring connections to the preheating unit. They found two damaged glow plugs as well. Total repair was 320€ including parts and labor. The engine preheat system now works perfectly, no more warning lights or smoke issues during acceleration. Really glad I asked here first instead of letting the previous shop replace expensive parts unnecessarily. The car electronics are all functioning normally now and cold starts are smooth again. Such a relief to have this properly fixed after weeks of uncertainty. Key lesson learned: finding a mechanic who actually specializes in diesel vehicle heater systems made all the difference. Thanks again for pointing me in the right direction with the wiring issue, saved me from a much bigger repair bill.