Is my oil pressure sensor or my oil pressure gauge faulty? on 2005 Cadillac Escalade

My oil pressure gauge fluctuates from zero to way past 80 but sometimes reads normal. When it's high or low, it will stay there for awhile. The dealer said they checked the pressure and said it was fine but that the oil pressure gauge was bad and the entire instrument cluster had to be replaced. Are they trying to hose me?

Asked by for the 2005 Cadillac Escalade
Probably not, these clusters give problems...... however you 'can' have another shop do a scan test to sweep gauges to confirm! Possible sending unit problem, sweep test will tell the tale!!