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

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

The codes below apply across common Heil models (ION, standard ICP). Meanings follow Heil’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 Heil furnace error codes

Diagnostic LED on the integrated furnace control (visible through a sight glass on the blower door). The LED is read by its state and flash count: a steady-on or off pattern indicates power/lockout status, while a repeating number of amber/red flashes (with a brief pause between groups) maps to a fault. A continuous slow flash means a call for heat is being served normally; a 'heartbeat' (1 flash per second) means power is present with no call for heat. Some two-stage and variable-speed (ION) controls also display two-part combination codes shown as a short flash group, pause, then a second group (for example 4 flashes, pause, 2 flashes = '4+2'). Codes are also printed on the SERVICE/wiring label inside the blower compartment.

Heil furnace error codes & what they mean

These are the Heil 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
LED Off	No power to the control board (no 24V / no line power reaching the control) pro repair	Furnace disconnect switch off; Tripped breaker or blown fuse; Blown low-voltage (3A) fuse on the control board	Confirm the furnace power switch (looks like a light switch on or near the furnace) is ON; Check the breaker labeled for the furnace and reset it once if tripped; Make sure the blower access door is fully closed and seated so the door switch engages
LED On, steady (not flashing)	Control circuit lockout / internal control fault — the board has detected a hard fault and is not flashing a numbered code pro repair	Internal control board malfunction; Control hardware/firmware fault requiring replacement or a power reset	Set the thermostat to OFF, then to HEAT, and confirm it is calling for heat; Try a single power cycle at the furnace switch or breaker to clear a temporary lockout; If the steady light returns, stop and call a licensed technician
LED On, continuous slow flashing	Normal operation with an active call for heat — no fault DIY-checkable	This is the expected indication during a normal heating cycle	No action needed; this indicates normal operation
LED On, 'heartbeat' (1 flash per second)	Normal operation, no call for heat — the control has 24V power and is idle/healthy DIY-checkable	This is the expected indication when the furnace is powered but not heating	No action needed; this indicates the control is powered and healthy; If you expect heat, set the thermostat to HEAT and above room temperature
2 flashes	Pressure switch did not open — the control sensed the pressure switch was already closed when it should have been open at the start of the cycle pro repair	Pressure switch stuck closed; Defective pressure switch; Obstruction or moisture in the pressure tubing	Go outside and confirm nothing is leaning against or blocking the intake and exhaust vent terminals; clear leaves, snow, ice, or debris; Try a single power cycle at the furnace switch
3 flashes	Pressure switch did not close, or reopened during the cycle — the control did not see proper draft proving pro repair	Blocked or restricted vent / improper vent sizing; Excessive wind affecting the vent; Defective inducer (draft) motor	Check that outdoor intake and exhaust vent terminals are clear of snow, ice, leaves, or nests; Confirm nothing has been leaned against the vent pipes outside; Try a single power cycle at the furnace switch
4 flashes	Limit circuit fault / limit circuit open — a safety limit (overheat) switch has opened pro repair	Dirty or clogged air filter restricting airflow; Restricted ductwork or closed/blocked registers; Loose blower wheel or defective blower motor	Check the air filter and replace it if it is dirty or clogged; Make sure supply and return air registers/vents are open and not blocked by furniture or rugs; Confirm the return-air grille is not obstructed
5 flashes	Abnormal flame-proving signal — flame was sensed when the gas valve was commanded off pro repair	Leaky gas valve; Gas valve stuck open; Defective control board sensing circuit	This is a gas-safety fault — do not attempt repairs; Set the thermostat to OFF and call a licensed HVAC technician
6 flashes	Failure to ignite, or flame was lost (flame signal weak or non-existent) while running pro repair	Dirty or oxidized flame sensor; Defective or worn hot-surface igniter; Low inlet gas pressure or gas supply interruption	Confirm the gas supply is on and other gas appliances (stove, water heater) are working; Make sure the gas shutoff valve at the furnace is in the open position; Try a single power cycle at the furnace switch to allow one more ignition attempt
7 flashes	Limit circuit lockout — repeated limit/overheat trips have locked the control out; it auto-resets after about 3 hours pro repair	Persistent airflow restriction (see code 4 causes); Dirty filter, restricted ducts, or failing blower	Check and replace a dirty air filter; Confirm registers and the return-air grille are open and unobstructed; Try a single power cycle to clear the lockout instead of waiting for the 3-hour auto-reset
8 flashes	Gas heating lockout — the control will not auto-reset; power must be cycled to clear pro repair	Miswired gas valve; Defective gas valve / control valve; Repeated ignition or flame faults reaching lockout	Confirm the gas supply is on and other gas appliances work; Try a single power cycle at the furnace switch to clear the lockout; If it returns, call a licensed technician
9 flashes	Medium-pressure switch, high-pressure switch, or PSR relay did not close or has reopened (two-stage / high-efficiency models). Diagnose using the same approach as code 3 pro repair	Restricted or improperly sized vent; Clogged condensate drain; Defective pressure switch or PSR relay	Check that outdoor intake/exhaust vent terminals are clear of snow, ice, and debris; Try a single power cycle at the furnace switch
10 flashes	Line voltage polarity reversed (or polarity/grounding fault) — the control requires correct line-voltage polarity to operate pro repair	Reversed line (hot) and neutral wiring; Open or poor equipment ground; Burnt wiring harness or damaged spot on the control board	This is an electrical wiring fault — do not open wiring; Set the thermostat to OFF and call a licensed HVAC technician
1+2 (1 flash, pause, 2 flashes)	Blower is energized after a normal power-up / blower-on indication — generally a normal status, not a hard fault DIY-checkable	Normal control behavior after power is applied or a cycle ends	Usually normal; no action needed; If the blower runs continuously and unexpectedly, set the thermostat fan setting to AUTO
1+5 (1 flash, pause, 5 flashes)	Blower motor lockout — the control auto-resets after about 3 hours pro repair	Failed or seized blower motor; Blower motor wiring fault; Control unable to confirm blower operation	Try a single power cycle at the furnace switch to clear the lockout; If it returns, call a licensed technician
3+5 (3 flashes, pause, 5 flashes)	Gas valve fault — a problem with the gas valve circuit (often associated with the valve wiring such as the red/yellow/orange leads) pro repair	Gas valve wiring fault; Defective gas valve; Defective control board valve circuit	This is a gas-valve fault — do not attempt repairs; Set the thermostat to OFF and call a licensed HVAC technician
4+1 (4 flashes, pause, 1 flash)	Blower motor fault — the blower failed to reach its expected speed (for example failed to reach about 250 RPM) pro repair	Failing or obstructed blower motor; Blower wheel obstruction or imbalance; Motor control / wiring fault	Check the air filter and replace if dirty; Confirm registers and the return grille are not blocked; Try a single power cycle at the furnace switch
4+2 (4 flashes, pause, 2 flashes)	Inducer (draft) motor fault — the inducer did not operate within expected parameters pro repair	Improper vent sizing or restricted vent; Failed or failing inducer motor; Wiring fault to the inducer	Check that outdoor intake/exhaust vent terminals are clear of snow, ice, and debris; Try a single power cycle at the furnace switch
4+3 (4 flashes, pause, 3 flashes)	Low/medium pressure switch open while the medium/high pressure switch is closed (two-stage high-efficiency draft fault) pro repair	Low gas pressure; Clogged condensate drain; Stuck or defective pressure switch	Check outdoor vent terminals are clear of snow, ice, and debris; Confirm the gas supply is on and other gas appliances work; Try a single power cycle at the furnace switch
6+1 (6 flashes, pause, 1 flash)	Ignition lockout — too many failed ignition attempts; the control auto-resets after about 3 hours (diagnose using code 6) pro repair	Dirty or oxidized flame sensor; Worn or defective hot-surface igniter; Low inlet gas pressure or gas interruption	Confirm the gas supply is on and other gas appliances work; Make sure the furnace gas shutoff valve is open; Try a single power cycle at the furnace switch to allow another ignition attempt instead of waiting 3 hours

Heil furnace codes we get called for most

6+1 (6 flashes, pause, 1 flash) — Ignition lockout — too many failed ignition attempts; the control auto-resets after about 3 hours (diagnose using code 6)

Typical causes include dirty or oxidized flame sensor; worn or defective hot-surface igniter; low inlet gas pressure or gas interruption. A few things are safe to check yourself (Confirm the gas supply is on and other gas appliances work; Make sure the furnace gas shutoff valve is open), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes 6+1 (6 flashes, pause, 1 flash) on Heil furnaces throughout Greater Vancouver.

2 flashes — Pressure switch did not open — the control sensed the pressure switch was already closed when it should have been open at the start of the cycle

Typical causes include pressure switch stuck closed; defective pressure switch; obstruction or moisture in the pressure tubing. A few things are safe to check yourself (Go outside and confirm nothing is leaning against or blocking the intake and exhaust vent terminals; clear leaves, snow, ice, or debris; Try a single power cycle at the furnace switch), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes 2 flashes on Heil furnaces throughout Greater Vancouver.

4 flashes — Limit circuit fault / limit circuit open — a safety limit (overheat) switch has opened

Typical causes include dirty or clogged air filter restricting airflow; restricted ductwork or closed/blocked registers; loose blower wheel or defective blower motor. A few things are safe to check yourself (Check the air filter and replace it if it is dirty or clogged; Make sure supply and return air registers/vents are open and not blocked by furniture or rugs), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes 4 flashes on Heil furnaces throughout Greater Vancouver.

1+2 (1 flash, pause, 2 flashes) — Blower is energized after a normal power-up / blower-on indication — generally a normal status, not a hard fault

Typical causes include normal control behavior after power is applied or a cycle ends. A few things are safe to check yourself (Usually normal; no action needed; If the blower runs continuously and unexpectedly, set the thermostat fan setting to AUTO), but the repair is a licensed, TSBC-certified gas technician job. HeatLand diagnoses and fixes 1+2 (1 flash, pause, 2 flashes) on Heil furnaces throughout Greater Vancouver.

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

Most Heil 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.

Heil furnace repair across Greater Vancouver

HeatLand has kept Metro Vancouver homes comfortable since 1999. Our licensed, insured technicians diagnose and repair Heil 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.

Heil furnace service areas

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

Heil furnace error code FAQs

Can I reset my Heil 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 Heil 6+1 (6 flashes, pause, 1 flash) code mean?

On Heil furnaces, 6+1 (6 flashes, pause, 1 flash) commonly indicates ignition lockout — too many failed ignition attempts; the control auto-resets after about 3 hours (diagnose using code 6). 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 Heil furnaces you didn’t install?

Yes. HeatLand is brand-agnostic and services Heil 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 Heil 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 Heil furnace repair cost in Vancouver?

It depends on the fault. Many Heil 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: