I know you are not going to like my post, but I had a 1996 E300D and loved the car. At approximately 40k miles the glow plug light would come on when I was driving. It would happen once or twice every 1,000 miles or so.

Mercedes worked on the car and could not solve the problem. It eventually started to come on once or twice a week. Every third or fourth time, it would start to trigger the check engine - check electronics light/display.

Mercedes worked on the car for 3+ years and 55k miles. At 95k miles they compensated me with enough cash so that I could end my lease prematurely.

They did the following work:
- EDC replacement
- 2 Engine wiring harnesses
- 3 sets of glow plugs
- 4 glow plug relays
- wired a test lamp from the glow plug to interior for testing
- replaced the ignition switch
- replaced the entire instrument cluster
- countless engine adjustments
- cleaned intake manifold, etc.
- countless other works - just shooting in the wind
- months and months in the shop and being driven by techs for weeks

I couldn't even pass emissions anymore because having the check engine light or codes stored is an automatic failure in this state.

Hopefully, yours is behaving like a normal diesel and indicating that there is problem with the glow plug relay or a glow plug. These glow plugs include an afterglow function so that they remain heated for a couple minutes after the engine is started.

With MB's approval, the dealer sold the car to a customer in Southern Colorado - with a binder of legal waivers. She doesn't have emissions to pass and has a very solid car - with just one exception. The difference is that she paid less than 10k for the car while I paid 40k.

If I was her, I would think I had a great car for the money. I had all the options and miss the car - just not the problem. I now have a 2002 CLK 320 Cabriolet.

I may tempt fate with a new 2004/5 E320 CDI diesel. Who knows...