Keep in mind, they will probably end up having to reprogram HPCM2 again, AFTER replacing the coolant level sensor. An undocumented "feature" is that the HPCM2 monitors the coolant level for 10 minutes AFTER the ignition is OFF or CONTINUALLY during active charging.
So replacing it without triggering the entire mess of DTCs again is a bit tricky. You must leave the car OFF with the hood open for 11+ minutes before changing the sensor, which is easy as it simply "pops" out of a small receptacle on the bottom of the reservoir.
WOT, could us regular folks just not clear the latched DTC fault with a cheap ODB-II tool or does this actually require a full program performed by the GM service dept? I take it this level sensor can be changed w/o draining or re-filling the 50/50 Dex-Cool. It would be cool if you could take a pic of your bypass. Does it create an open or short in order to 'fool' the HPCM2?