Lennox Furnace Error Codes — Meanings, Causes & Repair in Greater Vancouver

Seeing a fault code on your Lennox furnace? This guide explains what the most common Lennox furnace error codes mean, what’s safe to check yourself, and when to call HeatLand’s licensed, TSBC-certified gas technicians for Lennox furnace repair across Metro Vancouver and the Fraser Valley.

The codes below apply across common Lennox models (Signature, Elite, Merit, SLP98, SL280). Meanings follow Lennox’s documented fault codes — always confirm against your unit’s own manual, because exact wording can vary by model, control board and firmware.

How to read Lennox furnace error codes

Modern Lennox furnaces with a SureLight integrated control display a numeric 'E' code on a single seven-segment LED, flashed one digit at a time in sequence (e.g. E-2-5-0 for E250). The same E-codes appear on the iComfort/communicating thermostat as 'Alert Codes'. Older, non-communicating SureLight boards instead use a pair of LEDs (LED #1 / LED #2) that signal faults through slow-flash (1 Hz) and fast-flash (3 Hz) patterns rather than numeric codes.

Lennox furnace error codes & what they mean

These are the Lennox furnace codes our Greater Vancouver technicians see most. Anything marked pro repair involves gas, electrical, sealed-combustion or control-board work that must be done by a licensed gas technician (TSBC-certified in BC) — never open gas or electrical components yourself.

Code	What it usually means	Common causes	Safe to check yourself
E105	Device communication problem – no other devices found on the communication BUS pro repair	Miswired or loose communication (BUS) connections; High-voltage electrical noise source near the system (e.g. welder); Failed control or thermostat communication	Confirm the furnace power switch and breaker are on; Power-cycle the system once at the breaker (off 60 seconds, back on)
E110	Low line voltage (supply voltage lower than the nameplate rating) pro repair	Utility low-voltage / brown-out condition; Undersized or loose line-voltage wiring; Failed disconnect or breaker connection	Confirm the furnace switch and breaker are on; Check whether other appliances on the same circuit are dimming or struggling; Power-cycle once at the breaker
E113	High line voltage (supply voltage higher than the nameplate rating) pro repair	Utility over-voltage condition; Wiring or supply fault	Confirm the furnace switch and breaker are on; Power-cycle once at the breaker
E114	Line voltage frequency out of range (no clean 60 Hz power) pro repair	Power supplied by a generator or inverter with poor frequency; Utility power quality problem	Confirm the furnace is running on normal utility power, not a generator; Power-cycle once at the breaker
E115	Low 24V control voltage (normal range 18 to 30 volts). Control will restart automatically if the condition recovers pro repair	Failing or overloaded transformer; Shorted or pinched low-voltage wiring; Add-on accessory drawing too much current	Confirm the furnace switch and breaker are on; Power-cycle once at the breaker
E120	Unresponsive device on the communication BUS (often the outdoor unit slow to respond to indoor-unit polling) pro repair	Outdoor unit slow or failing to respond; Loose or miswired BUS connections; Power-up timing issue	Power-cycle the system once at the breaker; Confirm the outdoor unit disconnect is on (heat pump / AC systems)
E124	Active communicating thermostat signal missing for more than 3 minutes – equipment lost communication with the thermostat pro repair	Loose or damaged thermostat communication wiring; Thermostat power or hardware fault	Check that the thermostat display is on and set to Heat; Power-cycle the thermostat / system once
E125	Control failed self-check / internal hardware error (includes flame-sense circuit faults, pin shorts). Will restart if the error recovers pro repair	Failed or damaged integrated control board; Internal hardware fault	Power-cycle the furnace once at the breaker
E126	Failed internal control communication between the board's microcontrollers (control board hardware problem) pro repair	Integrated control board hardware fault	Power-cycle the furnace once at the breaker
E131	Corrupted control parameters – the system configuration needs to be verified / reconfigured pro repair	Configuration data corrupted; Control board needs reconfiguration or replacement if heating/cooling is unavailable	Power-cycle the system once at the breaker
E180	Outdoor air sensor failure. No error is shown if the sensor is simply disconnected; shown only if shorted or out of range pro repair	Shorted or out-of-range outdoor air sensor; Damaged sensor wiring	No homeowner action – note the code for the technician
E200	Hard lockout – flame rollout circuit open or previously open pro repair	Flame rollout caused by blocked heat exchanger or flue; Failed rollout switch; Combustion/venting problem – safety lockout	Confirm the furnace switch and breaker are on; Check that the flue/vent terminals outside are clear of snow, debris, or obstructions; Replace or clean a dirty air filter
E201	Indoor blower communication failure – the control is unable to communicate with the variable-speed blower motor (includes after a power outage) pro repair	Blower motor communication wiring loose or damaged; Failed blower motor module; Power interruption	Power-cycle the furnace once at the breaker
E202	Indoor blower motor mis-match – blower motor horsepower does not match the unit capacity (incorrect furnace size code selected) pro repair	Wrong unit size code configured on the control; Mismatched replacement blower motor	No homeowner action – note the code for the technician
E203	Appliance capacity / size is not programmed – no valid furnace size code has been selected on the control pro repair	Furnace size code not set during installation or after board replacement	No homeowner action – note the code for the technician
E204	Gas valve mis-wired pro repair	Gas valve wiring connected incorrectly; Gas valve fault	No homeowner action – note the code for the technician
E205	Gas valve control relay contact shorted pro repair	Failed gas valve relay on the control; Gas valve fault	No homeowner action – note the code for the technician
E207	Hot surface ignitor sensed open pro repair	Cracked or burned-out hot surface ignitor; Open ignitor wiring connection	Power-cycle the furnace once at the breaker; Confirm the furnace switch and breaker are on
E223	Low-pressure switch failed open pro repair	Blocked or restricted vent / combustion-air intake; Failed combustion air inducer; Failed or stuck-open pressure switch	Check that the intake and exhaust vent terminals outside are clear of snow, ice, debris, or nests; Replace or clean a dirty air filter; Power-cycle once at the breaker
E224	Low-pressure switch failed closed (contacts closed when they should be open) pro repair	Pressure switch stuck closed; Pressure switch wiring fault	No homeowner action – note the code for the technician
E225	High-pressure switch failed open pro repair	Restricted vent / combustion-air system; Failed combustion air inducer; Failed or stuck-open high-pressure switch	Check that the vent terminals outside are clear of obstructions; Replace or clean a dirty air filter; Power-cycle once at the breaker
E226	High-pressure switch failed closed (contacts closed when they should be open) pro repair	High-pressure switch stuck closed; Pressure switch wiring fault	No homeowner action – note the code for the technician
E227	Low-pressure switch open during trial for ignition or run mode pro repair	Restricted or blocked vent / combustion-air system; Failing combustion air inducer; Marginal venting or pressure switch	Check that the intake and exhaust vent terminals outside are clear; Replace or clean a dirty air filter; Power-cycle once at the breaker
E228	Unable to perform a successful pressure switch calibration pro repair	Vent system restriction; Pressure switch wiring connection problem	Check that the vent terminals outside are clear of obstructions; Power-cycle once at the breaker
E240	Low flame current in run mode pro repair	Dirty or corroded flame sensor rod; Poor unit ground; Weak or partial flame	Confirm the gas supply is on and other gas appliances work; Power-cycle once at the breaker
E241	Flame sensed out of sequence – flame still present when none should be pro repair	Gas valve leaking by / not fully closing	If you smell gas, leave the home and call your gas utility's emergency line and a licensed technician – do not attempt checks yourself
E250	Limit switch circuit open pro repair	Overheating from low airflow; Dirty air filter or blocked return/supply vents; Furnace overfired	Replace or clean a dirty air filter; Make sure return and supply registers are open and unobstructed; Power-cycle once at the breaker
E252	Discharge air temperature too high (gas heat only) pro repair	Low airflow (dirty filter, blocked ducts); Overfiring / incorrect input rate; Restricted ductwork	Replace or clean a dirty air filter; Make sure supply and return registers are open and unobstructed
E270	Soft lockout – exceeded the maximum number of ignition retries; no flame current sensed pro repair	No gas flow to burners; Failed ignitor not lighting the burner; Dirty flame sensor	Confirm the gas supply is on and other gas appliances work; Confirm the furnace switch and breaker are on; Power-cycle once at the breaker
E271	Soft lockout – exceeded the maximum number of retries; the last retry failed because the pressure switch opened (see E223) pro repair	Restricted vent / combustion-air system; Failing inducer; Marginal pressure switch	Check that the vent terminals outside are clear of obstructions; Replace or clean a dirty air filter; Power-cycle once at the breaker
E272	Soft lockout – exceeded the maximum number of recycles; the last recycle was caused by the pressure switch opening (see E223 / E225) pro repair	Restricted vent / combustion-air system; Failing inducer; Marginal pressure switch	Check that the vent terminals outside are clear; Replace or clean a dirty air filter; Power-cycle once at the breaker
E273	Soft lockout – exceeded the maximum number of recycles; the last recycle was due to flame failure (see E240) pro repair	Dirty flame sensor; Weak flame / poor ground; Marginal gas supply	Confirm the gas supply is on and other gas appliances work; Power-cycle once at the breaker
E274	Soft lockout – exceeded the maximum number of recycles; the last recycle failed because the limit circuit opened or the limit remained open longer than 3 minutes (see E250) pro repair	Low airflow from dirty filter or blocked vents; Overheating; Failed limit switch	Replace or clean a dirty air filter; Make sure return and supply registers are open and unobstructed; Power-cycle once at the breaker
E275	Soft lockout – flame sensed out of sequence (from an E241 fault); the flame signal is now gone (see E241) pro repair	Gas valve leaking by / not fully closing	If you smell gas, leave the home and call your gas utility and a licensed technician – do not attempt checks yourself
E276	Soft lockout – exceeded the maximum number of pressure-switch calibration retries (see E228) pro repair	Vent system restriction; Pressure switch wiring problem	Check that the vent terminals outside are clear of obstructions; Power-cycle once at the breaker
E290	Ignitor circuit fault – failed ignitor or triggering circuitry (see E207) pro repair	Failed hot surface ignitor; Failed ignitor triggering circuit on the control	Confirm the furnace switch and breaker are on; Power-cycle once at the breaker
E291	Restricted airflow – measured CFM is lower than what is needed for the minimum firing rate pro repair	Dirty air filter; Restricted or undersized ductwork; Closed or blocked registers	Replace or clean a dirty air filter; Make sure return and supply registers are open and unobstructed
E292	Indoor blower motor unable to start (seized bearings, stuck wheel, etc.) pro repair	Seized blower motor bearings; Stuck or obstructed blower wheel; Failed motor	Power-cycle the furnace once at the breaker
E294	Combustion air inducer motor amp draw is too high pro repair	Worn inducer motor bearings; Inducer wiring problem; Failing inducer motor	No homeowner action – note the code for the technician
E295	Indoor blower motor temperature is too high (motor tripped on its internal protector) pro repair	Worn blower motor bearings; High motor amperage; Restricted airflow causing motor overheating	Replace or clean a dirty air filter; Make sure return and supply registers are open and unobstructed; Power-cycle once at the breaker
E310	Discharge air sensor failure – no error if disconnected; shown only if shorted or out of range (activated during Field Test mode) pro repair	Shorted or out-of-range discharge air temperature sensor; Damaged sensor wiring	No homeowner action – note the code for the technician
E311	Heat rate reduced to match indoor blower airflow (furnace in cutback mode due to restricted airflow). Replace filter or repair duct restriction DIY-checkable	Dirty air filter; Restricted or undersized ductwork; Closed or blocked registers	Replace or clean a dirty air filter; Make sure return and supply registers are open and unobstructed
E312	Restricted airflow in cooling or continuous-fan mode is lower than the CFM setting – blower running at reduced CFM (cutback mode) to protect the motor DIY-checkable	Dirty air filter; Restricted or undersized ductwork (high external static pressure); Closed or blocked registers	Replace or clean a dirty air filter; Make sure return and supply registers are open and unobstructed
E313	Indoor or outdoor unit capacity mismatch (incorrect indoor/outdoor capacity code selected). Warning only – system operation is not impacted; clears when commissioning is exited pro repair	Incorrect capacity code configured during installation	No homeowner action – note the code for the technician
E347	No 24-volt output on Y1 to C with a non-communicating outdoor unit (Y1 / Stage 1 relay failed) pro repair	Failed pilot relay on the control board; Relay coil did not energize	No homeowner action – note the code for the technician
E348	No 24-volt output on Y2 to C with a non-communicating outdoor unit (Y2 / Stage 2 relay failed) pro repair	Failed pilot relay on the control board; Relay coil did not energize	No homeowner action – note the code for the technician
Dual-LED: both LEDs simultaneous SLOW flash	Normal operation – signaled when a heating demand is initiated at the thermostat (older non-communicating SureLight boards) DIY-checkable	Normal heating operation – no fault	No action needed – this indicates normal operation
Dual-LED: LED1 SLOW flash / LED2 OFF	Low flame signal (measures below ~0.7 microamps) on older non-communicating SureLight boards – flame sense rod needs cleaning/replacement pro repair	Dirty or corroded flame sensor rod; Poor ground	Confirm the gas supply is on and other gas appliances work; Power-cycle once at the breaker
Dual-LED: both LEDs ON steady	Flame rollout switch open (or the 9-pin connector is improperly attached) on older non-communicating SureLight boards pro repair	Flame rollout from a blocked heat exchanger or flue; Failed rollout switch; Loose 9-pin control connector	Check that the vent terminals outside are clear of obstructions; Replace or clean a dirty air filter
Dual-LED: LED1 ON steady / LED2 OFF	Open ignitor circuit on older non-communicating SureLight boards pro repair	Failed or cracked hot surface ignitor; Open ignitor wiring connection	Confirm the furnace switch and breaker are on; Power-cycle once at the breaker

Lennox furnace codes we get called for most

E227 — Low-pressure switch open during trial for ignition or run mode

Typical causes include restricted or blocked vent / combustion-air system; failing combustion air inducer; marginal venting or pressure switch. A few things are safe to check yourself (Check that the intake and exhaust vent terminals outside are clear; Replace or clean a dirty air filter), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes E227 on Lennox furnaces throughout Greater Vancouver.

E223 — Low-pressure switch failed open

Typical causes include blocked or restricted vent / combustion-air intake; failed combustion air inducer; failed or stuck-open pressure switch. A few things are safe to check yourself (Check that the intake and exhaust vent terminals outside are clear of snow, ice, debris, or nests; Replace or clean a dirty air filter), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes E223 on Lennox furnaces throughout Greater Vancouver.

E252 — Discharge air temperature too high (gas heat only)

Typical causes include low airflow (dirty filter, blocked ducts); overfiring / incorrect input rate; restricted ductwork. A few things are safe to check yourself (Replace or clean a dirty air filter; Make sure supply and return registers are open and unobstructed), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes E252 on Lennox furnaces throughout Greater Vancouver.

E201 — Indoor blower communication failure – the control is unable to communicate with the variable-speed blower motor (includes after a power outage)

Typical causes include blower motor communication wiring loose or damaged; failed blower motor module; power interruption. A few things are safe to check yourself (Power-cycle the furnace once at the breaker), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes E201 on Lennox furnaces throughout Greater Vancouver.

Is it safe to keep running a Lennox furnace with a fault code?

Most Lennox fault codes put the furnace into a safe lockout for a reason. You can safely check the basics — the furnace switch and breaker on, a clean air filter, the gas supply on, the thermostat set to heat and calling, and — on high-efficiency models — the condensate drain not blocked or frozen — and restart it once. If the code returns, stop and book a technician. If you ever smell gas, leave the building and call your gas utility’s emergency line or 911 first. If a carbon-monoxide alarm sounds, get everyone out and call 911. A rollout or repeated limit trip can signal a heat-exchanger or venting problem — don’t keep resetting it.

Lennox furnace repair across Greater Vancouver

HeatLand has kept Metro Vancouver homes comfortable since 1999. Our licensed, insured technicians diagnose and repair Lennox furnaces — ignition and flame-sensor faults, pressure-switch and venting problems, limit and rollout trips, blower and igniter issues, and control-board errors — including units we didn’t install. We’re brand-agnostic, carry common parts, and give you an honest repair-or-replace assessment with upfront pricing and a free estimate. If your furnace is beyond economical repair, we’ll show you right-sized, high-efficiency replacement options and the rebates available.

Need it sorted fast? We offer priority emergency furnace repair. Explore Furnace services, browse all furnace error codes by brand, or request a free estimate.

Lennox furnace service areas

We repair Lennox furnaces across Greater Vancouver and the Fraser Valley, including:

Lennox furnace error code FAQs

Can I reset my Lennox furnace myself?

Yes — power-cycling the reset button once is generally safe after you’ve checked the basics (the furnace switch and breaker on, a clean air filter, the gas supply on, the thermostat set to heat and calling, and — on high-efficiency models — the condensate drain not blocked or frozen). If the furnace faults again right away, stop and note the code — repeatedly resetting a furnace that keeps locking out can mask a real problem. Call a licensed, TSBC-certified gas technician to diagnose it.

What does the Lennox E105 code mean?

On Lennox furnaces, E105 commonly indicates device communication problem – no other devices found on the communication bus. Confirm the exact meaning against your unit’s manual — codes can vary by model and series — and have the repair done by a licensed, TSBC-certified gas technician. HeatLand fixes this across Greater Vancouver.

Do you repair Lennox furnaces you didn’t install?

Yes. HeatLand is brand-agnostic and services Lennox furnaces throughout Metro Vancouver and the Fraser Valley, whether or not we installed the unit. We carry common parts and give you an honest repair-or-replace assessment.

Is a Lennox furnace fault code an emergency?

No heat in cold weather is worth treating urgently. If you ever smell gas, leave the building and call your gas utility’s emergency line or 911 first. If a carbon-monoxide alarm sounds, get everyone out and call 911. A rollout or repeated limit trip can signal a heat-exchanger or venting problem — don’t keep resetting it. For priority furnace repair across Greater Vancouver, call (604) 330-3812.

How much does Lennox furnace repair cost in Vancouver?

It depends on the fault. Many Lennox codes point to sensors, ignition or pump parts — usually far cheaper than replacement. We give upfront pricing and a free estimate before any work.

More Furnace error-code guides

HeatLand repairs every major furnace brand across Greater Vancouver. More brand guides: