VW Caddy Diesel: Glow Plug Warning Light Nightmare

As someone with moderate car maintenance experience, I had a similar issue with my 2004 VW Golf TDI. The symptoms you describe match exactly what I encountered, persistent glow plug light, engine light illumination, and smoking during acceleration. Initially thought it was the glow plugs themselves, but after taking it to a workshop, they diagnosed a faulty connection between the control unit and the heating element. The wire harness had worn through, causing intermittent connections to the glow plug system. The repair was straightforward, they replaced the damaged wiring and connectors, costing 95€ in total. Since the fix, all warning lights cleared and the engine has been running smoothly without smoke issues. Before suggesting specific fixes, could you share: Have you scanned for error codes? Does the issue occur more frequently during cold starts? Are you experiencing any starting problems? Has there been any recent work done on the engine? This could help determine if your Caddy has the same underlying issue or if it might be something different with the glow plug system. One thing to note, if your control unit is indeed faulty, waiting too long could lead to increased fuel consumption and potential engine damage.

Thanks for the detailed suggestion regarding the glow plug system. After hooking up to diagnostics, error code P0674 appears consistently. The cold start issues are now more frequent, especially during the recent cold weather. Engine does struggle to turn over and vehicle stalling occurs occasionally. The last service was done at 58000km with standard maintenance only. No engine work was performed. Fuel consumption has noticeably increased over the past month. Will check the wiring connection points you mentioned. Makes sense this could be causing the multiple warning lights. My main concern is preventing any long-term diesel engine damage from running with faulty glow plugs during these cold starts.

Thanks for the additional details. P0674 specifically points to cylinder 4 glow plug circuit malfunction, which aligns with the cold start issues youre experiencing. The increased stalling and fuel consumption suggest the engine is compensating for poor combustion. Looking back at my Golf repair, the circuit malfunction also caused similar fuel economy issues. The diagnostic test revealed irregular voltage readings across the glow plugs, initially misleading us to think multiple glow plugs were faulty. A thorough inspection showed the control unit was actually working fine, the main issue was corroded connections at the glow plug terminals causing resistance in the circuit. The corrosion likely developed from moisture intrusion, common in these models. If you notice similar corrosion, cleaning the terminals and applying dielectric grease might resolve the issue without major parts replacement. However, given the age of your Caddy, it would be wise to: 1. Test voltage at each glow plug 2. Inspect the wiring harness for any visible damage 3. Check the control unit connections for proper seating Since youre already experiencing vehicle stalling, addressing this promptly will prevent strain on your starter motor and battery during these cold starts.

Thanks for the input. I took the Caddy to a trusted mechanic who confirmed the electrical diagnosis suggested here. They found significant corrosion on cylinder 4 glow plug connections and some wiring insulation damage. The engine misfire symptoms matched exactly what was described. They performed a complete diagnostic test which showed the control unit itself was functioning correctly. The main issue was the corroded connections causing poor conductivity to that cylinder. Final repair included: Cleaning all glow plug terminals, Replacing damaged wiring section, Applying protective coating, Full system reset Total cost was 180€ for parts and labor. Since the repair, cold starts are normal again with no warning lights or vehicle stalling. Fuel consumption has returned to normal levels and the smoke during acceleration is completely gone. Really appreciate the guidance here which helped pinpoint the actual issue before replacing expensive parts unnecessarily. Will definitely keep an eye on those connections during future maintenance to prevent similar problems.