Plumbing Questions? Ask a Plumber and Get Answers ASAP.
That should be the manual for it, let me know if you have something different,
as an over view see pages 18, 19 and 20 for the procedures to be followed for each of those error codes, then from there we will take some shortcuts to the most likely solutions.
Tell me about how old the water heater is, and if it has ever been flushed with any type of acid or white vinegar,
Use a hair drier to slowly warm the printed circuit card up to120F or a bit warmer, but not over 140F... if there is any change in the error codes or other furnace behavior... the card has a cracked micro circuit that opens and closes as the card expands and contracts... that proves a bad printed circuit card.
No change however does not prove the card is good however... but a change proves the card is definitely bad.
I will be in for a while longer tonight, if you miss me, I will pick your response up first thing in the morning.