Brand guide
A.O. Smith error codes
Match the equipment family and displayed code before following any check.
Official A.O. Smith material describes 1 flash as Low flame signal; the control continues to operate. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 2 flash as Pressure switch failed closed. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 3 flash as Pressure switch failed open. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 4 flash as ECO (Energy Cut Off) limit thermostat temperature limit was exceeded; the main burner is shut off. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 5 flash as Flame out of sequence sensed. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 6-1 flash as Retry limit exceeded (failed trial for ignition). This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 6-2 flash as Recycle limit exceeded: pressure switch/high limit opened. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 6-3 flash as Recycle limit exceeded: flame lost. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 6-4 flash as Recycle limit exceeded: flame out of sequence. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 7 flash as Flammable Vapor Sensor (FVS) lockout. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 8-1 flash as Flammable Vapor Sensor fault detected. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 8-2 flash as Temperature sensor fault detected. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 8-3 flash as Electronics fault detected. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.
Official A.O. Smith material describes 8-4 flash as Valve fault detected. This guide records the cited product-family scope, safety-reviewed owner checks, and service limits.