why does the oil pressure gauge read too high, not reset when engine turned off? on 2002 Chevrolet Avalanche 1500

It just started yesterday, the gauge reads 60 when turned off, needle goes all the way to the right when the engine is on. No oil leak noted, engine runs normally (temp ok, no noise).

My oil pressure did the same thing 2 days ago and my mechanic said it was my oil sending unit. Though i have nope tried to fix it(bc of money) maybe this will help you find the problem. plz keep me updated