I have a paloma ptg42pvn that shows a c4-12 code. I un-plug the unit for 5 or so minutes and it works fine until it shuts off, then the next time it fires the code c4-12 returns. unit works great after un-plugging. in coming gas psi is 12
Water Heaters - Rheem - Paloma PTG-42PVN / RTG2-42PVN Natural Gas Indoor