05 Siverado oil pressure too high
 

Recently my oil pressure guage started showing 80 psi but when i turned the ignition off the gauge would only go back to 40 and not all the way to zero. I changed the oil pressure sending unit and now the neddle goes all the way past 80 and as far to the right as it can go. Do you think it is the gauge or could it be something else?

I've read that sometimes the fuel gauge will do that when theres a bad ground, so possibly you have a bad ground.

sounds like the stepper motor is going bad in the gauge. you can check by putting a mechanical gauge in and see what psi you have, or use a scan tool.. my money would be on a bad gauge/cluster..

good luck