The OVP (overvoltage protection relay) is just what its name says.Its purpose is to protect the engine control unit from excessive voltage.Its unlikley that this is your problem though.Its very possible you have a air mass sensor going bad or possibly a ignition coil going bad.The 93 and some 94 year 104 engines had some problems with ignition coils made by "May Christy".
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Mercedes Benz Master Tech - Retired
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