Just to update while I am waiting for the engine to cool down so I don't melt my hands...
Cleared the codes, the P0300 didn't come back yet but all 4 O2 sensors show high voltage. S2b1 sensor reads 0 volts, 2 others read constant too high voltage and one does the right thing and fluctuates under 1 volt. Thinking it's odd all 4 sensors would be faulty so reading up on PCM right now. Seems TIPM could also somehow be involved which would be interesting with that recurring M13 fuse issue.
Once it cools down I'll check the no voltage O2 sensor connections and see if a little jiggle helps anything. Will give the others a look as well while I'm under there. Good news is without that P0300 I don't have to look for crank and cam sensors.
Just glad it's not freezing here in Canberra...
Will attach the code screenshot I snapped in case anyone wants to have a look.
