You should be able to get a cheapo gauge at any auto parts place, or
Kmart, etc. to verify gauge or engine problem. If you verify the engine is
good and gauge is bad then look for that original, correct gauge. If,
however, the gauge turns out to be good then start looking at the presure
releif valve and check that it is good. Also, when was the last time an
oil/filter change was done? ... or it could be the oil pump. More details
are needed like how many miles on engine, oil weight, etc.