On my 1998 E300 Diesel the glow plug indicator appeared yesterday after I started the car and it remains on along with the Check Engine Light.

The car starts and runs just fine. I plan on getting to this soon but don't know if it is just a glow plug out or if there is a problem with the relay.

Is there an easy way to determine.

I certainly don't want to be driving around with the plugs all on - that would only shorten their lives for certain.

I have searched around but don't find anything about the light remaining on permantly after starting.

All help appreciated.

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1991 300D 172,000 (totaled)
1998 E300 Turbodiesel 82,500

I can't be the only one with this problem - or can I? Any help please?

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1991 300D 172,000 (totaled)
1998 E300 Turbodiesel 82,500

I can certainly say that the glowplugs do not remain "on" while the engine is running.

I do not know much about your model of car, including the fact that it is a lot newer than mine.

But from my knowledge, in general, of diesel engines, I'm going to say that you most likely have a glow plug out. I wouldn't worry about the relay. I am familiar with testing the 300sd glow plugs with a meter, but I am unsure of the values the meter would display in order for you to determine which glowplug was at fault.

Off the bat, I'd say just do a general search on how to test the glowplug resistance with a multimeter through the wires, and check them. Even if you don't find the values, the odd ones out, assuming you know how to use a meter, are most likely the ones at fault.

Since your car still starts you probably only have 1 out, as once 2 go out, the car seems to get much harder to start. Your problem doesn't seem too bad, as you most likely have a single glow plug out.

Good Luck!

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1974 240d "Peace, Love and Empathy" - Kurt Cobain
1982 300sd "It all depends upon the Benz!" - Me
1983 300sd
1985 500sel
1992 300se