Heater will not ignite; display shows E01 shortly after a call for heat

Safety first: Turn off power at the breaker and shut off the gas supply valve before opening the heater cabinet. Allow the unit to cool completely.

Steps to try:

• Check gas supply: Verify the gas valve feeding the SunHeater pool heater is fully open. Confirm other gas appliances in the home work normally. If gas pressure is low or intermittent, contact your gas utility or a licensed gas technician.
• Inspect the igniter assembly: Remove the front panel and locate the hot surface igniter on the burner tray. Look for cracks, white spots, or heavy scaling. If damaged or heavily worn, replace the Hot Surface Igniter Assembly.
• Clean the flame sensor: The flame sensor is usually a small metal rod near the burner flame. Gently clean it with fine steel wool or a Scotch-Brite pad to remove oxidation. Do not sand aggressively. Reinstall securely.
• Check igniter wiring: Inspect the harness from the control board to the igniter for burns, loose connectors, or rodent damage. Reseat all plugs on the Ignition Control Board and igniter.
• Reset power: Restore power and gas, then call for heat from the pool controller or thermostat. Observe through the sight glass: the igniter should glow and burners should light smoothly. If E01 returns after several attempts, the igniter or ignition control board is likely faulty and should be replaced.

When to stop: If you smell gas, hear loud pops on ignition, or see flames rolling out of the burner compartment, shut everything off and call a qualified pool heater technician immediately.