OVP=overvoltage protection relay. It is like a UPS for the cars control units. It is located behind the battery with a number of control units. It is silver, smaller than the rest and has a fuse under a plastic cover on the top.
Since you have the ABS light on its very likely that the only problem is the fuse on top. It you pull the relay out of its mount you will be able to find the date code on the device. If it is the original (date code before prod date) I would advise replacing it. It has so many ways of failing that replacement can prevent intermittant problems.
Yes, partsshop should be able to provide it if you need one.
Bosch Master, ASE Master, L1
33 years MB technician