How do I fix an A04 display code?

Check your stack flu sensor. Sensor can not be jumped. As soon as the heater fires hold down the pool or spa button until the stack temp appears. At 500 degrees the heater will shut off giving a code. The heater should not restart. I would also check for wire damage based on the description of your issue and the board restarting on it own. You may also have damage to the "user interface board" , hard to say with out on site trouble shooting.

It is either a bad pcb board or you may have a short in the wiring.

AO4 is a PCB Board used for some of the Comfort Zone heaters distributed by Earth Wise. Try using the up, down and enter for a reset of the unit. If this does not work unplug and try again.

Try pushing up, down and enter at the same time. If that does not work unplug and try again this should reset if the PCB is good.

This is a error that can be fixed with a specific reset sequence. Follow this process carefully. The unit will not turn on for long and turns itself off after about a second so you need to execute step 2 immediately after step one.
Step 1 - Turn on heater
Step 2 immediately press no 1 on the keypad - this will display the error code H01 #68
Step 3 Hold down no 4 for approx 5 secs till the screen goes blank
Step 4 The screen displays all of the settings and resets
Note: you may need to do this a few times before it works - wait some time before retrying. If a reset will fix the problem this is the solution - if it is hardware a service call is required.

Appliances fault A04 has different meanings depending on the type of appliance. Please see below for further detauls:

Also see our video section for help.

Error: A04,
Machine: Dishwasher,
Type: EV02 Module,
Fault: The selected temperature was not reached within a given time.Check thermistor and heater


Error: A04,
Machine: Dishwasher,
Type: Standard Module + FDW70 + FDW75,
Fault: Heating fault.Check thermistor and associated wiring

Hope helps.

Comfort Zone heaters do not have a display board, they only had thermostat knobs.

Is it possible that you have a different model of heater?

I have a Richmond tankless water heater PTG2-42PVN. It will work for a very short time & then I get an error code of either C4 or C7. The remote control alternately flashes IL - 120

E0 error means Fixing Unit failure. It could be a dirty Thermistor. It could be an open Thermal Fuse. It could be an open Heater Lamp. Anyways, once the culprit has been isolated and corrected, the copier will need to be reset via "jumpering" certain points on DC Controller.