VW Eos Glow Plug Issues: Smoke and Warning Lights

Had a similar glow plug issue with a 2013 VW Passat diesel last winter. Having some experience with diesel engine maintenance, I recognized those symptoms immediately, continuous preheating lamp, check engine light, and smoke during acceleration are classic signs of glow plug system problems. Took it to my regular workshop where they diagnosed a faulty connection between the glow plug and its wiring harness. The cable insulation had worn down, causing intermittent contact. The repair involved replacing the damaged wiring and ensuring proper connections to prevent future issues. Total cost was 95€ and the car was ready within a day. The vehicle stalling and engine misfire symptoms disappeared completely after the fix. Regular car maintenance checks since then have shown no recurring issues with the glow plug system. Could you share more details about your Eos? Specifically: Current mileage, When did these symptoms first appear, Have you noticed any changes in fuel consumption, Does the smoke color appear black or blue, Does the problem worsen in cold weather This information would help determine if your issue matches what I experienced or if there might be other factors to consider.

Just had my routine service two weeks ago where they ran a diagnostic test that showed no issues. Now at 56245km, these symptoms appeared suddenly after a cold start last week. The smoke looks more black than blue and definitely gets worse during cold mornings. Fuel consumption seems higher than usual, though I have not tracked the exact numbers. The engine misfire is most noticeable during initial acceleration. This glow plug situation is particularly concerning since the car ran perfectly fine before. Will have the control unit checked as suggested, hoping its not a bigger issue with multiple faulty glow plugs.

Based on your description and mileage, this sounds exactly like what happened with my Passat. After getting the wiring fixed, I actually discovered that one glow plug had failed completely due to the electrical issues. The black smoke during cold starts is a telltale sign of incomplete combustion, which matches what I experienced. The sudden onset after running fine is typical of glow plug system failures. When my control unit started acting up, the engine performance deteriorated rapidly, especially during cold starts. The increased fuel consumption you are noticing likely occurs because the engine is compensating for poor combustion. While the wiring repair fixed my initial problems, I ended up replacing both the faulty glow plug and the control unit as a preventive measure. The complete repair including parts and labor came to 320€. The investment was worth it since proper car maintenance prevents more expensive issues down the line. The timing of your symptoms, especially after the cold start issues, strongly suggests this is indeed a glow plug system problem rather than something more serious. These issues typically surface during colder weather when the glow plug system is under more stress. Would suggest having both the control unit and the glow plugs tested individually. Sometimes the engine light comes on due to one component failing, but there might be others close to failing as well.

Thanks for the detailed feedback. Knowing these common symptoms with diesel engines helps narrow down the problem. My Eos is showing the exact pattern you described, the black smoke and cold start issues match perfectly. Definitely going to have both the control unit and individual glow plugs tested as suggested. The 320€ total cost seems reasonable considering the comprehensive fix. Better to address everything now rather than face bigger problems later. Will schedule the repairs this week since the cold weather is making the engine misfire and vehicle stalling more frequent. Really hoping its just the wiring and control unit like in your case. Going to keep tracking the fuel consumption and cold start behavior until the repair. Main concern is preventing any additional damage to the diesel engine. Will update once I get the final diagnostic test results and know exactly what needs replacing.