VW Scirocco Diesel: Glow Plug & Smoke Issues Solved

Had almost identical issues with my 2010 VW Golf diesel. The symptoms match perfectly, continuous preheating lamp, engine light, and exhaust smoke during acceleration. After a cold start, the engine would run rough for several minutes. With some experience working on diesel engines, I initially suspected the heating element system but wanted a proper diagnostic test to confirm. The workshop connected their diagnostic tool and found that the glow plug control unit was receiving incorrect signals due to a faulty cable connection. The fix involved replacing the damaged wiring and ensuring proper connection to the control unit. Total cost was 95€ including diagnostic work. The engine misfire issues disappeared completely after the repair. Would you mind sharing: Does the problem occur more frequently during cold starts? Have you noticed any changes in fuel consumption? Are there any additional warning lights on the dashboard? Did you get any error codes read from the engine control unit? This information would help determine if your issue is identical to what I experienced with my Golf. These symptoms can sometimes indicate other related problems with the preheating system.

Thanks for sharing your experience. Same symptoms on my Scirocco with 14091km, the engine feels particularly rough during cold starts, and fuel consumption has increased noticeably over the past month. Had it scanned at my last service and got error code P0671 which points to the heating element circuit. The vehicle stalling has become more frequent, especially during the first few minutes of operation. Between the error code and symptoms matching yours exactly, it sounds like I should check the wiring to the glow plug control unit first. Will get the connections inspected and report back on what they find. The repair cost you mentioned seems reasonable if it solves these issues.

Thanks for the update. The P0671 code and symptoms on your Scirocco definitely match what I experienced with my Golf. The vehicle stalling during cold starts was particularly frustrating for me too. After fixing the wiring connection to the glow plug control unit, my diesel engine ran much smoother. The repair resolved not just the cold start issues but also eliminated the excessive smoke during acceleration. The engine light and preheating lamp warnings disappeared completely. One thing to note, while checking the wiring, have them inspect all glow plugs as well. In my case, one glow plug showed signs of wear, though it wasnt causing immediate problems. Since the system was already being serviced, I had it replaced preventively for an additional 45€. The improved fuel consumption alone made the repair worthwhile. The engine misfire issues during cold starts completely disappeared after addressing the wiring problem. Let us know what they find during the inspection. These heating element circuit problems are fairly common on our engine type, and usually fixable without major expense.

Thanks for the helpful responses. I had the Scirocco checked today and you were absolutely right, the diagnostic test revealed damaged wiring between the glow plug control unit and the heating elements. The mechanic found corrosion on two of the connectors, likely from water intrusion. Total repair came to 140€ including parts and labor. They replaced the damaged wiring harness section and two glow plugs that showed wear during inspection. The car maintenance report indicated all other components of the preheating system were in good condition. After the repair, the engine light turned off and cold starts are now smooth with no smoke from the exhaust. Fuel consumption has returned to normal levels. The stalling issues have completely disappeared. Really appreciate the guidance, saved me from potentially replacing the entire control unit unnecessarily. Will make sure to have the connections checked during future services to prevent similar issues.