HVAC Code Lookup

Lennox fault codes

44 documented codes for Lennox furnaces, each cited to the manufacturer's own manual. Lennox furnaces use two different diagnostic systems. Merit/Elite 80-95% single- and two-stage units (ML180, ML193, EL195, EL296E) use a SureLight integrated control with a single red LED that flashes a count (1-13). Variable-capacity and communicating units (SLP98V, SLP99V, SL280V, EL296V, EL296E) use a seven-segment display that shows alphanumeric alert codes (E105, E200, E223, E292 ...). The E-code set is shared across the iComfort/SureLight variable-capacity control family, so the same code number means the same thing on an SLP98UHV and an EL296UHE. Armstrong Air, AirEase, Concord and Ducane are Allied Air brands also owned by Lennox International but use different control boards and a different code list - do not assume these codes carry over..

Furnace codes

CodeMeaningSeverity
11 rapid flash (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe 120-volt line power feeding the furnace has hot and neutral reversedWarning
22 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe control does not see an acceptable earth groundWarning
33 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe burners failed to light during a heat call, or a flame that was lit went out before the heat demand was satisfiedWarning
44 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe flame signal the control reads back from the flame sensor is too weakWarning
55 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsWatchguard lockoutSoft lockout
77 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe primary or secondary limit switch is open, meaning the furnace got too hotSoft lockout
88 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe flame rollout switch is openSafety fault
99 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe pressure prove switch did not close when the combustion air inducer started, or it opened part way through the heat demandWarning
1010 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsWatchguard lockout because the pressure switch opened five times during a single heating demandSoft lockout
1111 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe pressure switch contacts were already closed before the combustion air inducer was turned onWarning
1212 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe control is sensing flame when the gas valve is not energizedSafety fault
1313 rapid flashes (1/2 second on, 1/2 second off), then the LED stays off for 3 seconds and repeatsThe 120-volt supply to the furnace is below the acceptable rangeWarning
E105Device communication problemWarning
E110Low line voltageWarning
E111Line voltage polarity reversedWarning
E112Ground not detectedWarning
E113High line voltageWarning
E115Low 24 volt control powerWarning
E124The furnace has not heard from the communicating thermostat for more than three minutesWarning
E125The control failed its own self-checkHard lockout
E200Hard lockoutSafety fault
E203The furnace capacity or size has not been programmed into the controlHard lockout
E204Gas valve mis-wiredSafety fault
E205The gas valve control relay contact on the board is shorted, meaning the control cannot reliably shut the gas valve off through that relaySafety fault
E207The hot surface ignitor is sensed as openSoft lockout
E223The low pressure switch failed to close when it should haveWarning
E224The low pressure switch failed closedWarning
E225The high pressure switch failed to closeWarning
E226The high pressure switch failed closedWarning
E227The low pressure switch opened during the trial for ignition or while the furnace was runningWarning
E229Information onlyStatus
E240Low flame current while the furnace is runningWarning
E241Flame sensed out of sequenceSafety fault
E250The limit switch circuit is open, meaning the furnace overheatedSoft lockout
E270Soft lockoutSoft lockout
E271Soft lockoutSoft lockout
E273Soft lockoutSoft lockout
E274Soft lockoutSoft lockout
E290Ignitor circuit faultSoft lockout
E291Restricted air flowWarning
E292The indoor blower motor is unable to startHard lockout
E310Discharge air temperature sensor failureWarning
E311The furnace has reduced its heat rate to match the airflow the blower can actually deliverWarning
E312Restricted air flow in cooling or continuous fan modeWarning

Manuals used for this page