VW Eos Diesel Glow Plug System Malfunction Warning

As a VW Touran TDI 2004 owner, I faced nearly identical preheating issues last winter. The symptoms match perfectly, persistent preheating lamp, engine warning light, and excessive smoke during acceleration. The car electronics diagnostic revealed failing glow plug connections and a deteriorating preheating unit control module. The root cause was corroded wiring connectors between the preheating control unit and the glow plugs. This created resistance in the ignition system, causing incomplete combustion and the smoke. While the vehicle heater seemed to work, the preheating cycle was actually incomplete. The repair involved: Testing each glow plug individually, Replacing corroded wiring connectors, Installing a new preheating control module, Resetting engine management system This was a serious electrical issue that required immediate attention since continued use could damage the engine and fuel injection system. The problem is common in VW diesel engines from that production period due to their preheating unit design. The vehicle returned to normal operation after repairs, no warning lights, proper preheating cycles, and clean acceleration without smoke. Recommend having it checked soon as these symptoms typically worsen and can lead to starting problems in cold weather.

Thanks for detailing your experience. Did something similar with my Eos last spring with the preheating unit and ignition system problems. Your defective part symptoms match what I experienced exactly, especially the issues with the car electronics and smoke. Really helpful to know about the corroded connectors, considering my cars age, this might be worth checking. The heating module on these VWs can be tricky. Do you remember roughly what you paid for the complete fix? Also curious if any other related issues have come up since the repair was done? Sometimes these electrical gremlins have a way of coming back.

After fixing the car electronics fault at the shop, everything has worked perfectly for months now. The mechanic found the main problem was indeed the preheating control unit connection, just like your Eos symptoms suggested. The repair was straightforward, costing 95€ to fix the defective cable and plug connection in the heating module. No electrical faults or engine preheat issues since then. The warning lights disappeared completely after the repair, and cold starts are smooth now. The smoke during acceleration is also gone, confirming the preheating system is working correctly. For what it is worth, the mechanic mentioned these connector problems are quite common in VW engine preheat systems of this age. Regular checks of the preheating control unit connections can prevent bigger issues down the line. My advice would be to have those connectors inspected during your next service to catch any early signs of corrosion.

After getting your response, I finally took my Eos to a trusted mechanic last week. The engine preheat system was definitely the culprit. Found multiple issues with corroded connectors in the preheating control unit, explaining all those warning lights and smoke. Total repair came to 280€ including labor, pricier than expected but worth it. The mechanic replaced the defective parts in the vehicle heater system and cleaned all electrical connections. The car electronics diagnostic also revealed a small issue with the main control unit which they fixed while at it. Really glad I got it sorted before winter. Car runs perfectly now, no more warning lights or smoke during acceleration. Started right up this morning despite the cold. Thanks again for pointing me in the right direction with the connector issue. Saved me from another frustrating experience with an unreliable repair shop.