Yep all by it self the check engine light will be on when you get in the car and will go back off when the car warms up or if the out side temps is about 35* -- and no the key is not in the car and its locked parked on the street -- i think it could be a leaking board and when it warms up it is ok but what box ?????????? anyone have seen this before -- jz

No, never. I did not think that was "powered up" when the ignition was off.

Is the light on with the key off?

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

It would help to know the year / model, not just "124", but my guess is that the alarm system (marked Becker, under the passenger carpet) is malfunctioning. Unplug it and see if the light goes away.

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Gone to the dark side

- Jeff

thanks for the tips and sorry its a 1988 E300 and to answer with the car locked and key in pocket the check engine light glows but only when its real cold and left out side over night - when you turn the key to start is comes on bright but as the car warms up 5 / 6 min it goes out and stays out, than sometime during the time you leave it parked again and come back if it has gone below 35 it starts to glow again ???? BUT if its in a parking garage and it is not in the real cold it does not come on -- only at start up than goes right off as it should --

i will go and check for the alarm under rug and see if its that ( disconect it )

but it has no affect on the car other than being on when you get in the car, in the very cold day or night -- jz

Had this problem last month. Turned out in my case to be a drain thru the voltage protection relay.

Had this same problem as well on my 95. Replaced the OVP and it was all better. I took the old one apart and the board was all corroded.

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

My wife's 1993 400e is doing the same thing, guess I'll change the OVP and see if the problem goes away.

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Closing the store
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No OVP on the 400E.