QuestionThe problem began about 24,000 miles ago (86,000 mi). The check engine light came on and VW diagnostics said that a glow plug was bad, so I replaced the plug. Within months after that, the light was on again and another plug was bad. I replaced it and the other two old plugs. Six months ago the light was on again and I was told by VW that the harness and 3 of 4 glow plugs needed replacement, due to corrosion. Ironically, just pulling the harness off the plugs and then reattaching it solved the problem, first for about 2 months, then about 2 weeks. I talked to a Ford diesel tech and he suggested sanding the tips of the plugs that connected to the harness. I tried this with poor results. I decided to replace the harness, sand the glow plug tips, and see the result. After about 2 more months, the light is back on. Basically, I start the engine and in about 30 sec the check engine light comes on.
I have been told that the slight corrosion that forms on the plug tips/harness connectors, is sufficient to trigger the check engine light. Obviously, I can still start the engine, but in the winter, it may take some more cranking. I live in Western Washington, so really cold weather is not a big problem. But I am tired of replacing plugs/harnesses.
When I talked to the VW tech and service manager, they basically said that they had never seen a problem like this. Yet someone I know who also has a TDI has the same problem and he doesn't have a good solution, except to ignore the check engine light.
Answer
dielectric_grease
Roger,
As nice trick I learned in the military and has served me well; First clean all the contacts with electrical contact cleaner. Then use a regular pencil eraser to polish the contacts. This will get the oxidation off. Then apply dielectric grease to the contacts; it is sort of like magic, in that it protects from further corrosion, does not prevent conduction at the contact points, but will not conduct (short out) between contacts.
- Rick
