I had the oil pump installed in my 2004 EXT at 225K miles.
Granted the truck is currently down and waiting on a new engine.
But, that problem is not caused by the low oil pressure situation that prompted me to install the new Melling high volume oil pump.
As a matter of fact, the oil pressure in that engine is the best it has ever been for the entire time I have owned it.
If this were my truck and all I was seeing was an error indicating a low voltage value from an (or several) oil pressure sensor and NOT any indication from the engine itself that it is experiencing any problems, I would be having a new oil pump installed before I put a new engine in it.
A reading of 23 PSI at hot idle is not dangerously low oil pressure.
It may be low enough to trip an error code, but I have come to understand the GM spec for acceptable oil pressure is 10 PSI per 1000 RPM.
At idle RPM, you are well above that.
That's lower than I would like to see, but if it supplies enough oil to the engine for GM, I would have to think your engine is not damaged at this point.
Now, are you experiencing anything else wrong with the engine other than the one error message you are reporting?
If not, then the engine is most likely fine and the error is being thrown because the oil pressure, regardless of the oil pressure sensor you are using at the time, is low enough to trigger an error code.
That code does not mean the engine is about to self-destruct just yet.
A new oil pump may solve that problem once and for all.
Oh, and I didn't even buy my EXT until it had 116K miles on it and my Z-66 had 241K on it.
You have a fresh truck as far as I am concerned.