Lennox International Inc Lennox Furnace Diagnostic Codes, Error Codes, and Fault Codes Explained

Integrated Control Diagnostic Codes

FLASH CODE	STATUS / ERROR DESCRIPTION
(X + Y)
	FLASH CODE DESCRIPTIONS

Pulse	A 1/4 second flash followed by four seconds of off time.
Heartbeat	Constant 1/2 second bright and 1/2 second dim cycles.
X + Y	LED flashes X times at 2Hz, remains off for two seconds, flashes Y times at 2Hz, remains off for four
	seconds, then repeats.
Pulse	Power on − Standby.
Heartbeat	Normal operation − signaled when heating demand initiated at thermostat.
	FLAME CODES
1 + 2	Low flame current −− run mode.
1 + 3	Flame sensed out of sequence −− flame still present.
	PRESSURE SWITCH CODES
2 + 3	Low pressure switch failed open.
2 + 4	Low pressure switch failed closed.
2 + 5	High pressure switch failed open.
2 + 6	High pressure switch failed closed.
2 + 7	Low pressure switch opened during ignition trial or heating demand.
	LIMIT CODE
3 + 1	Limit switch open.
	WATCHGUARD CODES
4 + 1	Watchguard −− Exceeded maximum number of retries.
4 + 2	Watchguard −− Exceeded maximum number of retries or last retry was due to pressure switch opening.
4 + 3	Watchguard −− Exceeded maximum number of retries or last retry was due to flame failure.
4 + 5	Watchguard −− Limit remained open longer than three minutes.
4 + 6	Watchguard −− Flame sensed out of sequence; flame signal gone.
4 + 7	Ignitor circuit fault −− Failed ignitor or triggering circuitry.
4 + 8	Low line voltage.
	HARD LOCKOUT CODES
5 + 1	Hard lockout −− Rollout circuit open or previously opened.
5 + 2	Control failed self check, internal error (control will restart if error recovers).
5 + 3	No Earth ground (control will restart if error recovers).
5 + 4	Reversed line voltage polarity (control will restart if the error recovers).
5 + 6	Low secondary (24VAC) voltage.

Error Code Storage

The ignition control stores the last ten error codes in memory. The codes are retained in case of power loss.

Error Code Review

1 − Short R (2) to (1). Within 1/2 second, the STATUS LED will stay lit continuously to indicate that the short was sensed.

2 − Continue to hold the short between R (2) to (1). After 5 seconds, STATUS LED will go from being continuously

lit to off. This indicates that error code review is pend- ing.

3 − Remove R (2) to (1) short within ten seconds of STA- TUS LED turning off. This activates error code review.

4 − Last ten error codes will be flashed on the STATUS

LED.

5 − After final error code is indicated, STATUS LED will

flash to indicate normal operation.

Clearing Error Codes

1 − Short R (2) to (1). Within 1/2 second, the STATUS LED will stay lit continuously to indicate that the short was sensed.

2 − Continue to hold the short between R (2) to (1). After 5

seconds, STATUS LED will go from being continuously

lit to off.

3 − Continue to hold the short between R (2) to (1) beyond ten seconds after STATUS LED has turned off. STA- TUS LED will turn on, indicating that error codes have been cleared.

4 − Remove R (2) to (1) short. STATUS LED will flash to in-

dicate normal operation.

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