VW Polo TDI Glow Plug Issues Causing Smoke

I had almost the exact same issue with my VW Golf TDI from 2019. The symptoms were identical, persistent glow plug indicator, engine light, and smoke during acceleration. With some experience working on diesel engines, I recognized these classic signs of glow plug system problems. After running a diagnostic test at my regular workshop, they found a damaged wire harness connecting to the glow plug control unit. The heating element was getting irregular voltage due to a loose connection. The mechanic showed me where corrosion had developed on the plug connections. The fix was straightforward, they replaced the wiring harness and cleaned all connecting points to ensure proper contact. Total cost was 95€ including the diagnostic work. Since then, no more warning lights or smoking issues. To help diagnose your case more accurately, could you share: Does the vehicle stalling occur specifically when the engine is cold? Have you noticed any starting problems? Did you get any specific error codes from previous diagnostic scans? How many kilometers has your Polo covered? The issues between our cars sound very similar, but these details would help confirm if you are dealing with the same root cause.

Thanks for sharing your experience. My car has 34596km on the clock and had its last service done just 2 months ago. The cold start problems began showing up recently, with the engine struggling most when temperatures drop below 10 degrees. The diagnostic test showed error code P0671 which points to the glow plug circuit. The workshop quoted 250€ for a complete glow plug replacement, but given your experience with the wiring harness issue, I will have them check the connections first. The heating element might not be the core problem if there are loose or corroded wires affecting the diesel engine preheating system.

Thanks for providing those additional details. Since having a similar issue with my Golf TDI, I learned more about diesel engine preheating systems. The error code P0671 can indeed be misleading, it often triggers for wiring issues, not just faulty glow plugs. The cold temperature correlation and recent service timing suggest checking the wiring should be your first step. My engine misfire and smoke issues showed up the same way, worse in cold weather. The glow plug control unit was getting faulty signals due to those corroded connections. 250€ for complete glow plug replacement seems high if the plugs themselves are not the issue. My repair cost of 95€ for the wiring fix resolved all symptoms. If your workshop finds similar harness damage, the repair should be in the same range. For proper car maintenance, ask them to: 1. Test voltage at each glow plug connection point 2. Inspect the full length of the wiring harness 3. Clean all connector terminals 4. Check the control unit connections The engine light should clear once the proper voltage reaches all glow plugs. Let us know what they find after inspecting the wiring.

That information really helps, I will definitely ask the workshop to inspect the wiring before replacing any parts. The winter weather had me worried about potential engine damage, but knowing there could be a simpler fix with the harness gives me some relief. I will schedule an appointment tomorrow and make sure they check all the electrical connections first, especially since the error code could point to either the plugs or wiring. With my car having similar cold start problems and vehicle stalling patterns as your case, I suspect the root cause might be the same. The price difference between a wiring repair versus full glow plug replacement is significant enough to investigate this route first. Will update once the control unit and connections have been properly tested. Thanks for helping me potentially save both time and money on unnecessary replacements.