A6 Diesel Glow Plug System Causing Smoke and Alerts

As an A4 diesel owner who faced similar symptoms, those signs strongly indicate glow plug system issues. The control unit and connections are common failure points in these engines, especially around that mileage range. When my vehicle started showing identical symptoms, constant preheat light, engine misfire during cold starts, and excessive smoke, it turned out the glow plug control unit had corroded connections. The smoke occurs because diesel fuel isnt properly combusting during startup and acceleration. The fix required: Testing individual glow plug resistance, Checking wiring harness for breaks, Replacing corroded control unit connectors, Performing system reset with diagnostic tool Vehicle stalling became frequent before repairs, particularly during cold weather. This is definitely a serious issue that needs professional attention, as improper diesel combustion can damage injectors and valves if left unchecked. Recommend having all glow plugs tested individually, since the control unit might not be the only problem. The wiring harness should also be inspected for damage, as connection issues often accompany control unit failures in these models.

Had exact same problems on my A6 diesel not long ago. Glow plug control unit and two of the plugs needed replacing due to corrosion. Car maintenance costs can really add up but its much cheaper than letting it get worse. The cold start issues completely disappeared after the repair and the vehicle runs perfectly now. Quick question, do you recall roughly how much the repair ended up costing you? Also curious if youve had any other issues pop up since getting it fixed? Would be good to know what to watch out for with these diesel engine repairs.

After getting my A6 checked by a certified mechanic, the diagnostic test confirmed the glow control unit was defective. The total repair came to 95 Euro, which mainly covered fixing a faulty cable connection to the heating element. Much more affordable than I initially feared. Since the repair, the diesel engine has been running smoothly with no vehicle stalling or cold start problems. The smoke issues completely cleared up and the warning lights haven't returned. The regular car maintenance schedule has kept everything working properly for the past few months. For reference, having the entire glow plug system tested was crucial, it helped identify that the issue was just the connection rather than needing a full unit replacement, which would have cost significantly more. Would definitely suggest getting a thorough system check if similar symptoms appear.

Thanks for the input. Finally took my car to a new mechanic who was much more thorough than my previous one. The total bill came to 420 Euro which included replacing the glow plug control unit and two heating elements that were completely shot. The engine light disappeared right after the repair and cold starts are perfect now. No more diesel engine smoke issues either. The mechanic also caught some minor wiring problems while doing the work and fixed those at no extra charge. Been about 3 weeks since the repair and car maintenance has been smooth sailing. Really glad I didn't wait longer as the mechanic mentioned the failing glow plugs could have eventually led to serious engine misfire problems. The peace of mind was worth every cent spent on getting it properly diagnosed and fixed.