IIRR, if you getting the pressure switch error and NOT the low oil pressure warning, the switch could be stuck in the grounded position. Again, IIRR, the ECU checks to see if the switch is working. If it finds it showing pressure when the engine is not running, it will cause the error. It will also have an error if it stays showing no pressure when running, but then I think it throws the no oil pressure code as well.
Just some thoughts,
Tom