That's not it. I think that is the fuel Pump relay.

The OVP should be under the hood, passengers side, behind a black plastic panel up agaist the firewall.
It is a tall , aluminum can w/fuse on top..[ see the pic I posted]
I don't have the exact location for that mosel, so maybe some C220 owners here here does.

Do a Search for OVP in the Archieves ..top of page. You will find that relay was changed to a new syle b/c the old ones were troublesome..compare those numbers when you get it out. New=000 540 67 45. Old= 000 540 52 45
If it is the old #, change it regardless. ..and check the fuse.

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A Dalton