Furrion water heater not working with fresh water

[Adinai]

Hi,
Have a strange new problem. Had our 22 XLR Micro Boost Toy hauler for 3 years- bought it in 21. It has solar on the roof and a tankless water heater. This weekend at the motorcycle track, we had power but no water hookups. Filled the fresh water tank as usual. Tried to get a shower and the thermostat started beeping and looked like the power to it was fading in and out. Got 3 different error codes before I gave up. E1, E5 and E7. Husband tried and it worked fine. Next night, neither of us got a shower in the camper anyway.
Got home this week and pulled the water heater exhaust off (E5 error), blew out the hose- nothing seemed to be in there. Tried the hot water, same problem. Hooked it up to city water, it all works exactly like it should. We didn't have the camper hooked to power either way. The pump and lights run off the solar. Gas was turned on - both tanks and the water heater was on both ways trying the water. The only thing we changed was the water input during our test.
We've never had any issues with the tank water getting hot as we just recently found a way to hook up to water at one of the tracks. I"ve dug all over the web trying to find answers.

Stumped in NC!
Andria

[Adinai]

Follow up... decided it might be related somehow to the fresh water pump, even though we have good water pressure on the cold side. We pulled the panel to get to the pump and found and cleaned the filter there which was minimally dirty. Still no change. E1 and E5 codes on the thermostat and no hot water.

One thing I have noticed on the thermostat. Previously when I turned on the hot water, the temp would drop from 115 to 72 then you would see it climb up 85, 97, etc...to 115 and voila- hot water within about 10 sec. Now it doesn't drop and after a few seconds we get the error codes and the entire thermostat looks like it is going to go off- lights flash like it doesn't have enough power.

Still stumped!