What's the best way to get at and remove the oil pressure sending unit on 2003 chevy avalanche?

On both the V6 and V8 engines the Oil Sensor is located on top of the engine at the rear. You will need to remove the top of the intake manifold to get to it.

i would have thought the work would take between 30 and 60 minutes max, if your refering to the temp/pressure unit ,so get the repair shop you choose to give you their hourly charge ,most repairers would give a precise quote for this sort of job so best to contact them direct

I would want to know what the actual oil pressure is. The sending unit or the gauge on the dash could have failed.
There is a pressure relief valve to prevent oil pressure from going too high, but staying at 80psi would not be good for a long time.

Locate oil pressure sending switch on side of engine block(small black switch with one wire plugged onto it )kinda looks like a big spark plug.Unplug clean contact and plug back in.If gauge still not working need to replace switch.

spend the 12 dollars and get a universal mechanical oil pressure gauge, remove the oil sending unit on truck and screw new gauge into and start truck. Does it read pressure? I know people will say just replace oil sending unit but i like to visually check for a true oil pressure than to trust a light, at least you will know what pressure your motor has. if you have pressure then replace the sending unit. Most of the time when the sending unit goes bad your oil pressure gauge in the truck will run at 80 psi all the time. Since you have a light the sending unit just says it isn't getting pressure which turns a light on. So be safe and do as i suggest, if there is no pressure at the mechanical gauge then i hate to say it but you may have a bad oil pump. I honestly just think you have a bad sending unit,if you want just replace it and if lights go off thats good, but you still don't know what the pressure is and if you feel comfortable with this then do so.

Oil pressure sending unit is located behind the intake, reach your hand behind the intake a little to the drivers side and you should feel the sensor

Check the oil pressure sensor..

Start up with the engine cold, should be 60-65 psi Start up with engine hot and also running in gear idling 42-48psi
Any other readings could be a bad oil pressure sending unit or a oil pressure relieve valve which is located on the block where the remote oil line is bolted to. Good luck and keep me posted.

Oil pressure gauge is not getting good ground. Check wire.

Not sure what engine you have, most 4.8, 5.3, 6.0s are WAAAY back in the middle of the engine facing the drivers side, very difficult to get to.