Hayward Poolheater Error Codes

All Hayward poolheater error codes with step-by-step troubleshooting, multimeter specs, and OEM part numbers.

11 error codes

Code	Meaning	Severity	Difficulty
10	The heater failed to establish or sustain a flame after multiple ignition attempts and has entered a hard lockout. highintermediate	high	intermediate
A1	The water temperature sensor (thermostat sensor) is reading outside its valid range, indicating a failed sensor, a wiring fault, or actual water temperature outside operating limits. moderateintermediate	moderate	intermediate
AO	The combustion air pressure switch didn't close during startup, which means the board couldn't confirm the blower was moving enough air to safely exhaust combustion gases. So ignition gets blocked as a safety measure. highintermediate	high	intermediate
BD	A blower drain or combustion air pressure fault, most commonly caused by a blocked condensate drain on condensing H-Series models or a combustion air pressure switch fault. moderateintermediate	moderate	intermediate
BO	The combustion blower motor or combustion chamber has exceeded safe temperature limits, triggering the thermal overheat safety lockout. highintermediate	high	intermediate
CE	A communication failure between the heater control board and the display panel, remote controller, or pool automation system. moderateadvanced	moderate	advanced
HUB	Reference guide for all Hayward H-Series pool heater fault codes. The board detects out-of-range conditions in combustion, water flow, or sensor circuits and displays a two-letter or numeric code to point you at which system tripped. lowbeginner	low	beginner
IF	Ignition Failure means the heater tried to light the burner multiple times and just couldn't establish or hold a flame. highintermediate	high	intermediate
LO	Water flow dropped below 20 GPM, so the flow switch couldn't close. The control board sees an open switch, interprets that as unsafe conditions for the heat exchanger, and locks out the burners completely until proper flow is restored. highbeginner	high	beginner
NOT-HEATING	LO means the pressure switch isn't seeing enough water flow to safely fire the burner. HI means the high limit thermostat tripped because something got too hot. IF means the igniter tried three times to light the burner and failed every time. All three are safety shutdowns, not actual heater failures. moderateintermediate	moderate	intermediate
RESET	A reset on a Hayward pool heater is the process of clearing a lockout condition or fault code from the control board memory to allow the unit to attempt a new ignition cycle. moderatebeginner	moderate	beginner