WPS Stuck Closed / Water Sw Open
The water-flow switch is closed during a valve-change sequence or open during a heat demand. Verify pump operation, valve position, filter condition, and water flow before checking the switch.
H2O Sensor Fail
The water-temperature sensors are open, shorted, or disagree. Inspect the sensor circuits and wiring before replacing a sensor or control.
Aux Ctrl Fault 2 / 3 / 5 / 6 / 8
The digital control detected a ROM, RAM, analog-reference, multiplexer, or clock fault. Record the exact number and follow the current manual's control-board diagnostic path.
Ign Ctrl Fault 2 / 3 / 5 / 6 / 7
The ignition control detected a ROM, RAM, analog, flame-sense, or execution fault. Record the exact number and have the ignition-control circuit diagnosed by qualified service.
Hi Water Temp
Water temperature exceeded 108°F. Stop heating and verify actual temperature, circulation, and sensor operation before resetting the heater.
Hi Limit 1 Fault / Hi Limit 2 Fault
The named high-limit circuit is open. Verify water flow and inspect the limit circuit, outlet temperature, heat exchanger, and bypass condition before reset.
Blocked Vent / Vent Temp Limit
The vent/field switch or vent-temperature limit is open. Shut the heater down and have the vent path, switch circuit, and vent-temperature cause inspected.
Air Flow Sw Open / Air Flow Sw Closed / 5 Min Ind Off / Fan Lockout
The inducer airflow switch did not match the commanded fan state; three fan-switch faults in one demand create Fan Lockout. Check the inducer, switch, tubing, relay, and wiring before clearing the lockout.
Ignition Failure / Ign 60 min Delay / Ignition Lockout
Flame was not established within the permitted trial sequence. Verify fuel type and supply, gas-valve operation, ignition wiring, igniter, grounding, and flame proving through qualified service.
MV Output Fault / Flame w/o CFH
The gas-valve output is not in the commanded state or flame is sensed with the valve closed. Shut off the gas supply and have the valve and ignition control inspected immediately.
Low Temp Lockout / Low Voltage
Water is below 36°F, or control supply is below 20 V. Verify actual water temperature and have the low-voltage supply and transformer checked.
Flue Over Temp / Flue Sense Fail / Blocked Drain
The flue is too hot, its sensor circuit failed, or the condensate-drain switch is closed. Shut the heater down and have venting, sensor wiring, combustion, and condensate drainage inspected.
Fan RPM Fault
Actual fan speed differs from target by more than 500 RPM. Check for obstruction, loose wiring, blower power, and motor-control operation through qualified service.
Remote Error / Clock-Fireman Sw
Both Pool and Spa inputs are energized, or the fireman/remote circuit is open. Correct the remote dry-contact wiring and controller state.
EOL (at startup)
Stuck MODE button. Check the MODE button on the control panel for a stuck or jammed switch.
