Check the resistance on all the plugs ,since i have 1 bad one the light comes on for a short time after the engine is running. It is explained in my owners manual that is an indication of a fault in the system,was my first tip off that i had a bad plug. My $.02 Don

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Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles