I recently purchased a 2006 Avalanche and the oil pressure gauge just tops at 80 when the engine is started. I anticipate that it is the sending unit. Does the 2006 5.3L have the plastic screen filter mentioned?
My 2013 threw a code and the oil pressure gauge went to zero yesterday. I immediately stopped and check the oil. It was fine. Had the code read and cleared this morning. Then the pressure gauge pinned hard right. Then back to zero. Then it coded again. Seems obvious it is a bad sending unit. Not going to bang myself up trying to change it as DIY, particularly because I do not have the suggested, necessary tools. If I did, I might make an afternoon of it as a test of my patience.
Bunch o' threads here about how to do it should you want to take a stab at it.