01 Tahoe 5.3 4wd, 204k miles

[Skunkape]

Lost oil pressure. Jumps to about 20 at start up and drops to 0, jumps to about 25 under load/ driving and drops back to 0 at stop. Replaced sensor with GM unit and no change. Does this vehicle have an oil sensor filter screen?

 

[SnowDrifter]

Hook up a mechanical gauge, go from there. It'll rule out any electronical bits

Also: It's common for the pickup tube o-ring to leak and cause the pump to suck air.

I would avoid driving the vehicle until this is sorted

 

[clandr1]

Check this thread. It might be your oil pickup tube o-ring.

https://www.tahoeyukonforum.com/threads/no-oil-pressure-at-start-up-2001-tahoe.67664/

edited to add: about a year ago I dropped my oil pan, removed the oil pickup tube, replaced the o-ring, and reinstalled with a new gasket in about 3 hours. Not too bad a job, and the gasket & o-ring doesn't cost that much at the dealer.

 

[swathdiver]

Does this vehicle have an oil sensor filter screen?

No it does not.

It's probably the O-Ring, if that is fine check your camshaft bearings.