Heil Furnace Error Codes

Error CodesWhat this meansHow to fix it
LED flashing like a heartbeatControl has 24 VAC powern/a
Two LED flashesUnit’s pressure switch didn’t openCheck for an obstruction in the pressure tubing
Three LED flashesUnit’s pressure switch didn’t close or reopenedCheck for: excessive wind; if it’s the proper vent size; defective inducer motor; defective pressure switch; inadequate combustion air supply; disconnected or obstructed pressure tubing; or restricted vent
Four LED flashesLimit circuit fault: either a limit or flame rollout is openCheck for: restricted vent; loose blower wheel; excessive wind; dirty air filter; or defective blower
Five LED flashesAn abnormal flame proving signal, the flame is likely proved while the gas valve is de-energizedCheck for a leaky gas valve or a gas valve that is stuck open
Six LED flashesFailure to ignite or the flame sensor was lost while runningCheck for: an ungrounded flame sensor; defective hot surface ignitor; control ground continuity; inadequate flame carryover; or rough ignition
Seven LED flashesLimit circuit lockoutA lockout will occur if the limit or flame rollout is open for longer than 3 minutes. Control will auto-reset after 3 hours.
Eight LED flashesGas heating lockout, control won’t auto-resetCheck for a miswired gas valve or a defective control valve
Ten LED flashesPolarity is reversedReview instructions to correct polarity
1 + 2Blower is on after power upOccurs if the unit is powered up during a call for heat or opens while the blower is on delay
6 + 1Ignition lockoutControl will auto-reset after 3 hours
LED is offSecondary voltage fuse is openCheck whether the door switch isn’t closed or for a short circuit
LED is onControl circuitry lockoutWill auto-reset after 1 hour
LED is solidGas valve relay is stuck while open, flame sense circuit failure, or software-check errorReset power to clear the lockout and then replace control if status code repeats itself