Hayward Poolheater Error Codes

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

10 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 did not close during startup, indicating insufficient combustion air flow or a restricted vent. 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 covering all Hayward H-Series pool heater error codes and fault indicators. lowbeginner	low	beginner
IF	Ignition Failure - the heater attempted to light the burner multiple times and could not establish or hold a flame. highintermediate	high	intermediate
LO	Water flow through the heater has fallen below the minimum required threshold, triggering a safety lockout to protect the heat exchanger. highbeginner	high	beginner
NOT-HEATING	LO, HI, IF, and Bypass Valve Fixes mediumintermediate	medium	intermediate