To test the lubrication system a good technician will test for engine oil pressure (with a pressure gauge) and if oil pressure is good then the only other issues are electrical. The engine oil pressure sensor, wiring from sensor to instrument cluster or the instrument cluster itself. Some rare occasions engine oil sludge has plugged or restricted the hole opening to the engine oil pressure sensor causing a false oil pressure reading. So you may what to look at the engine oil pressure sensor first for a high pressure reading. Engine oil pressure should increase when accelerating and drop back down to normal at idle.
Do you have the correct engine oil in the engine and do you change the oil and filter regularly?
Engine sludge can cause high oil pressure by restricting oil flow through engine.
I'm not sure what vacuum valve you mentioned in relation to engine oil pressure.
Let me know if this answers your question or if you have any more questions.
Talk to you soon, TY
Friday, August 23rd, 2013 AT 11:11 PM