Table of Contents
Furnace error codes help you understand why your heating system shuts down or struggles to run. Each brand communicates issues through LED blinks, digital numbers, or alpha-numeric codes. Learning how to read these signals makes troubleshooting faster and helps you decide what you can fix yourself and when it is time to call a professional.
This guide covers furnace error codes used across Canada, common causes, and what you should do next. It includes airflow issues, pressure switch faults, ignition lockouts, flame sensing problems, electrical failures, and safety lockouts.
How Furnace Error Codes Work
Most modern furnaces show codes through the control board located behind the small viewing window. Depending on the brand, you may see:
- Flashing red or green LEDs
- Short and long blink patterns
- Two-digit flash codes
- Seven segment number displays
- Alpha-numeric codes such as E2.1 or E3.2
These signals tell you whether the issue relates to airflow, ignition, flame sensing, electrical polarity, condensate, or safety components like rollout switches and limit switches.
How to Read Your Furnace’s Error Code
- Turn off the furnace power at the switch.
- Remove the access panel to view the control board.
- Count how many times the indicator light blinks and note the speed.
- If there is a display, write down the number or letter sequence.
- Compare the pattern to the code chart on the furnace door or in the installation manual.
- Restart power to confirm if the code reappears.
These steps apply to popular Canadian brands including Trane, Lennox, Carrier, Rheem, Goodman, Amana, Ducane, American Standard, Bryant, Payne, Ruud, RunTru, AirEase, and Ameristar.
Common Symptoms Linked to Furnace Error Codes
Many homeowners notice symptoms before checking the error code. These patterns help identify what type of issue you are dealing with:
- Furnace turns on for a few seconds then shuts down
- Blowing cold air or air that never fully heats
- Furnace starts repeatedly without completing a cycle
- Clicking without ignition
- Burners light then go out after 5 to 10 seconds
- Vents are producing weak airflow
- Outdoor vent pipes are frosted or blocked
- Water pooling under the furnace from condensate issues
- A smell of gas or unusual sounds near startup
Symptoms combined with the code help narrow down the exact problem.
Complete Furnace Error Code Lookup Table (Grouped by Brand)
Goodman Furnace Error Codes
| Code / Light Pattern | Meaning | Common Causes / First Checks |
|---|---|---|
| Light ON, no flashes | No signal from thermostat | Thermostat wiring, settings, or power to thermostat |
| Light OFF | Control board not powered | Breaker, switch, door switch, loose connections |
| 1 flash | Ignition failure / retries exceeded | Dirty or failed flame sensor, bad igniter, gas supply problem |
| 2 flashes | Pressure switch stuck closed | Shorted pressure switch, inducer issues, wiring faults |
| 3 flashes | Pressure switch stuck open | Blocked or loose pressure tubing, vent issues, inducer problems |
| 4 flashes | High limit open | Dirty filter, blocked ductwork, flue restrictions, wiring faults |
| 5 flashes | Flame sensed with gas valve off | Leaking gas valve, stuck valve, failed flame sensor |
| 6 flashes | Rollout switch open | Cracked or blocked heat exchanger, blocked vent, low gas pressure |
| 7 flashes | Low flame signal | Low gas pressure, dirty or mispositioned flame sensor |
| 8 flashes | Igniter problem | Failed igniter, loose igniter wiring, damaged harness |
| 9 flashes | Open pressure switch with inducer running | Cracked or blocked pressure hose, faulty pressure switch |
| Continuous flashing | Line voltage polarity reversed | Hot/neutral reversed, grounding issue |
Amana Furnace Error Codes
| Code / Light Pattern | Meaning | Common Causes / First Checks |
|---|---|---|
| Constant red | No thermostat signal | Thermostat wiring, no 24 V signal, transformer issues |
| Constant flashing | Polarity reversed | Line voltage polarity, ground connections |
| 1 flash | Ignition retries exceeded / flame not proven | Flame sensor, igniter, gas supply, wiring to sensor |
| 2 flashes | Draft inducer not running or pressure switch fault | Inducer motor, pressure switch, blocked vent, condensate |
| 3 flashes | Pressure switch open | Pressure switch tubing, vent obstructions, wiring |
| 4 flashes | Pressure or high limit problem | Clogged filter, blocked drain tubes, wiring, limit switch |
| 5 flashes | Flame present with no call for heat | Slow closing gas valve, valve leakage |
| 7 flashes | Flame sensor fault | Dirty, damaged, or misaligned flame sensor |
Trane Furnace Error Codes
| Code / Light Pattern | Meaning | Common Causes / First Checks |
|---|---|---|
| Slow constant blink | Normal operation | No action needed |
| Fast constant blink | Normal operation | No action needed |
| Red constant ON | Control failure | Control board fault, wiring, power quality |
| Red constant OFF | No control power | Breaker, switch, transformer, loose connections |
| 2 blinks | Flame failure, retries exceeded | Gas supply, flame rod, wiring, dirty burners |
| 3 blinks | Pressure switch problem | Blocked vent, plugged condensate drain, pressure tubing |
| 4 blinks | Temperature or high limit fault | Plugged filter, plugged secondary heat exchanger, duct restrictions |
| 5 blinks | Flame signal when none expected | Leaking or stuck gas valve, flame sensor fault |
| 6 blinks | Line polarity reversed / poor ground | Hot/neutral reversed, loose ground |
| 7 blinks | Gas valve circuit error | Gas valve, wiring to valve, control relay |
| 8 blinks | Low flame sense signal | Weak flame, low gas pressure, dirty flame sensor |
| 9 blinks | Igniter check / igniter fault | Check igniter element and wiring |
Carrier Furnace Error Codes
| Code / Light Pattern | Meaning | Common Causes / First Checks |
|---|---|---|
| Continuous OFF | No 115 V or 24 V to control | Power to furnace, transformer, fuse, breaker |
| Continuous ON | Control powered, no active fault | Normal if furnace is idle |
| Rapid flashing | Line voltage polarity reversed | Check incoming wiring, twinning kit if used |
| 1 blink | No previous stored code | Fault history cleared after power interruption |
| 2 blinks | Blower on after power up | Blower runs briefly after power is restored |
| 3 blinks | Limit or rollout lockout | Limit switches, airflow, blocked ducts, rollout condition |
| 4 blinks | Ignition lockout | Flame sensor, igniter, gas supply, ignition sequence |
| 2-1 | Gas heating lockout | Gas valve wiring, control board valve output |
| 2-2 | Abnormal flame proving signal | Flame sensed with valve closed, leaking gas valve |
| 2-3 | Pressure switch did not open | Stuck pressure switch, blocked tubing, vent issues |
| 2-4 | Secondary voltage fuse open | Short in 24 V wiring, blown low-voltage fuse |
| 3-1 | Pressure/vent/aux limit did not close or reopened | Inducer, vent sizing, pressure switch, combustion air |
| 3-3 | Limit or rollout switch open | Dirty filter, blocked ducts, blower faults, combustion air supply |
| 3-4 | Ignition proving failure | Flame sensor cleanliness, grounding, gas valve, igniter |
Lennox Furnace Error Codes
| Light Pattern | Meaning | Common Causes / First Checks |
|---|---|---|
| Red fast flash / green slow flash | Reversed polarity | Electrical wiring and grounding |
| Red slow flash / green fast flash | Low flame signal | Flame sensor, gas pressure, burner condition |
| Red slow flash / green solid | High limit switch open | Filter, blower wheel, duct restrictions |
| Red off / green slow flash | Draft inducer or pressure switch fault | Inducer motor, vent piping, pressure tubing, power switch |
| Red on-on-off / green on-off-on | Control board failure | Board diagnostics, wiring checks, replacement if needed |
| Red/green alternating slow | Flame failure | Pilot or ignition sensor, gas supply, ignition sequence |
| Red/green alternating fast | Voltage or grounding problem | Main ground connection, line voltage quality |
Ducane Furnace Error Codes
| Code / Light Pattern | Meaning | Common Causes / First Checks |
|---|---|---|
| Red ON | Normal operation | No action needed |
| Red OFF | No power | Breaker, connections, fuse, service switch |
| 1 red flash | Flame present with valve closed | Dirty flame sensor, slow-closing gas valve |
| 2 red flashes | Pressure switch closed with inducer off | Pressure switch stuck, debris in tubing, inducer faults |
| 3 red flashes | Low fire pressure, rollout, or limit open | Heat exchanger, vent, gas pressure, limit devices |
| 4 red flashes | High limit switch open | Filter, blower wheel, airflow restrictions |
| 6 red flashes | Pressure switch cycle lockout | Blocked vents, condensate drain, pressure switch |
| 7 red flashes | No ignition lockout | Flame sensor, igniter, filter, gas supply |
| 8 red flashes | Too many flame dropouts | Unstable flame, sensor or igniter failure |
| 9 red flashes | Polarity / phasing error | Wiring, line voltage phasing |
| Green flashing | High heat demand, high pressure switch open | Filter, blower wheel, airflow issues |
American Standard Furnace Error Codes
| Flash Count | Meaning | Common Causes / First Checks |
|---|---|---|
| 2 flashes | Flame dropping / blowing cold air | Unstable flame, gas pressure, flame sensor |
| 3 flashes | Pressure switch issue | Vent restrictions, pressure tubing, switch contacts |
| 4 flashes | Limit switch problem | High temperature, poor airflow, limit switch |
| 6 flashes | Polarity or grounding issue | Check line polarity and ground connection |
| 7 flashes | Gas valve problem | Valve coil, wiring, control signal |
| 9 flashes | Ignition or igniter circuit fault | Igniter element, wiring, control |
| 22 flashes | Flame quality problem | Burner condition, gas pressure, flame carryover |
Bryant Furnace Error Codes
| Code / LED Pattern | Meaning | Common Causes / First Checks |
|---|---|---|
| RED LED1 ON | Emergency heat mode | Heat pump issues, backup heat operation |
| RED LED2 ON | Microprocessor fault | Reset procedure, control board replacement if persistent |
| YELLOW LED3 ON | High heat operation | Normal in high stage |
| GREEN LED4 ON | Low heat operation | Normal in low stage |
| RED LED2 flashing | Line voltage polarity reversed | Hot/neutral reversed, wiring check |
| 1-1 | No recent faults | Normal; history shows no errors |
| 1-2 | Blower calibration lockout | Airflow/CFM setup, blower speed configuration |
| 1-3 | Limit switch lockout | Repeated limit trips, airflow, gas input, limits |
| 1-4 | Ignition lockout | Ignition sequence, flame sensor, gas supply |
| 2-1 | Model selection error | Model plug or jumper configuration |
| 2-2 | Setup switch error | Thermostat calls with incorrect DIP switch settings |
| 2-3 | Invalid blower airflow selection | CFM/tonnage settings out of range |
| 2-4 | Secondary voltage fuse open | Short in 24 V wiring, blown low-voltage fuse |
| 3-1 | Pressure switch did not close or reopened | Vent, inducer, pressure switch, tubing, combustion air |
Rheem Furnace Error Codes
| Display Code | Meaning | Common Causes / First Checks |
|---|---|---|
| 10 | One-hour lockout active | Recent repeated fault; identify root cause before reset |
| 11 | Ignition failure | Igniter, gas supply, flame sensor, wiring |
| 12 | Low flame detected | Low gas pressure, dirty burners, flame sensor |
| 13 | Flame lost | Unstable flame, draft changes, gas supply |
| 14 | Flame when valve should be closed, leaking valve | Flame when valve should be closed, leaking valve |
| 20 | Twinning fault | Twinning wiring configuration between furnaces |
| 22 | High limit problem | Airflow, duct restriction, filter, high temperature |
| 26 | Line/neutral reversed | Polarity reversed, grounding issues |
| 33 | Rollout switch problem | Flame rollout condition, severe combustion problem |
| 55 / 57 | Pressure switch fault | Blocked vent, pressure tubing, inducer operation |
| 58 / 59 | Water or condensate problem | Condensate drain blockage, trap, pump issues |
| 61 | Blower problem | Blower motor, capacitor, wiring |
| 93 | Control problem | Control board diagnostics, replacement |
Ruud Furnace Error Codes
| LED Pattern | Meaning | Common Causes / First Checks |
|---|---|---|
| LED steady ON | Normal operation | No action needed |
| 1 flash | No flame detected after three tries | Igniter, flame sensor, gas supply, ignition sequence |
| 2 flashes | Pressure switch stuck open / inducer problem | Pressure switch, vent, inducer motor, tubing |
| 3 flashes | Limit open or rollout tripped | Blocked vent, loose blower wheel, dirty filter, defective blower |
| 4 flashes | Pressure switch stuck closed | Obstruction in pressure tubing or switch contacts stuck |
| 6 flashes | Line/neutral reversed | Wiring, control board ground |
RunTru Furnace Error Codes
| Display Code | Meaning | Common Causes / First Checks |
|---|---|---|
| E01 | Internal control fault | Reset power; control board diagnostics or replacement |
| E2.1 | Ignition retries exceeded | Gas valve, supply pressure, igniter, flame sensor |
| E2.2 | Flame established then lost repeatedly | Dirty or failed flame sensor, wiring, inconsistent gas flow |
| E3.1 | Pressure switch shorted | Switch stuck, wiring, venting problems |
| E3.2 | Pressure switch open | Cracked or blocked pressure hose, faulty switch, loose wiring |
| E04 | High limit / rollout / reverse airflow | Dirty filter, blocked vents, cracked or blocked heat exchanger |
| E05 | Flame detected when off | Gas valve leaking or stuck, dirty or failed flame sensor |
| E6.1 | Line polarity reversed | Wiring to furnace, polarity |
| E6.2 | Poor or missing ground | Ground connection, bonding |
| E6.3 | Igniter relay fault or igniter open | Igniter resistance, wiring, gas line, filter |
| E7.1 | Gas valve energized when it should be off | Stuck-open valve, flame sensor, wiring issues |
| E08 | Low flame current | Dirty or damaged flame sensor, low gas pressure |
| E09 | Inducer limit or condensate switch open | Blocked condensate drain, blocked vents, pressure switch |
| E12 | Open fuse | Low airflow, wiring, failing components, blown fuse |
AirEase Furnace Error Codes
| Diagnostic Code | Meaning | Common Causes / First Checks |
|---|---|---|
| E105 | Device communication problem | Wiring, electrical noise near system |
| E110 | Low line voltage | Supply voltage, wiring, control board |
| E113 | High line voltage | Power outside range, supply issues |
| E200 | Hard lockout – rollout circuit open | Blocked airflow, cracked heat exchanger, low gas pressure |
| E223 | Low pressure switch failed open | Blocked vents, faulty pressure switch |
| E224 | Low pressure switch failed closed | Defective switch, inducer or vent issues |
| E240 | Low flame current (run) | Dirty or damaged flame sensor, grounding |
| E250 | Limit circuit open | Restricted airflow, clogged filter, duct issues, component failure |
| E270 | Soft lockout – no flame current sensed | Gas flow, igniter, flame sensor |
| E275 | Soft lockout – flame out of sequence | Gas valve leakage, faulty sensor |
| E295 | Blower motor temperature too high | Poor airflow, motor bearings, amperage draw |
Ameristar Furnace Error Codes
| Diagnostic Code | Meaning | Common Causes / First Checks |
|---|---|---|
| E01 | Internal control fault | Control board issue, power reset, replacement if needed |
| E2.1 | Ignition retry limit reached | Gas valve, gas supply, flame sensor, igniter |
| E2.2 | Flame established then lost / pressure switch open | Faulty wiring, dirty flame sensor, gas flow problems |
| E2.3 | Gas valve not energizing when expected | Valve failure, wiring, control output |
| E3.4 | Pressure switch open | Blocked airflow, broken switch, pressure hose issues |
| E04 | High limit / rollout / reverse airflow | Clogged filters, blocked vents, cracked or blocked heat exchanger |
| E05 | Flame detected when not expected | Defective sensor, leaking or stuck gas valve, electrical issues |
| E6.1 | Line polarity reversed | Hot/neutral wiring, polarity |
| E6.3 | Igniter relay fault or igniter open | Bad igniter, flame sensor, filters, gas line issues |
| E7.1 | Gas valve energized when it should be off | Valve stuck open, flame sensor or wiring problems |
| E08 | Low flame current | Dirty or faulty flame sensor, low gas pressure |
| E09 | Inducer limit or condensate switch open | Blocked condensate drain, vent restrictions, pressure switch |
| E12 | Open fuse | Dirty or failing components, low airflow, wiring fault |
Airflow and Venting Problems
Pressure Switch Errors • Blocked Vent • Condensate Blockages
Airflow faults are the most common source of furnace error codes in Canada. Cold climate conditions often lead to ice or snow blockage at the vent pipe that prevents the pressure switch from proving airflow.
Typical codes include:
- Pressure switch stuck open or stuck closed
- Blocked vent or poor draft
- Condensate drain blocked
- Inducer motor not proving
- Low airflow due to a dirty filter
First steps:
- Replace the filter
- Check outdoor intake and exhaust for frost, snow, or debris
- Flush the condensate trap and tubing
- Inspect pressure switch hoses for cracks or water
- Restart the furnace
If the code returns after clearing airflow, a licensed technician should inspect the inducer motor, measure draft pressure, check vent sizing, and confirm there are no internal blockages.
Ignition and Flame Sensing Problems
Ignition Lockout • Flame Failure • Low Flame Signal
Ignition problems occur when burners fail to light or the flame sensor cannot detect a stable flame.
Common error triggers:
- Dirty flame sensor
- Faulty hot surface igniter
- Low gas pressure
- Loose ground
- Intermittent flame dropout
- Flame sensed when the gas valve should be off
First steps:
- Turn off power
- Remove and clean the flame sensor with fine abrasive
- Ensure the gas supply valve is fully open
- Reset the furnace
If the furnace continues to fail ignition, a technician will test igniter resistance, measure flame current in microamps, verify burner carryover, and check the gas valve and control board.
Limit Switch and Rollout Errors
High Limit Open • Rollout Switch Open • Overheat Faults
When temperature rises beyond safe levels, the furnace opens the limit switch to prevent overheating. This often occurs due to restricted airflow or blower problems.
Typical causes:
- Dirty or restrictive furnace filter
- Closed or blocked supply vents
- Dirty blower wheel
- High static pressure
- Poor combustion
- Cracked or blocked heat exchanger
Steps you can take:
- Replace the filter
- Open all vents
- Check return air grilles
- Restart the furnace
Professional inspection is required if the rollout switch opens. A rollout event may indicate unsafe burner operation or a compromised heat exchanger.
Electrical and Control Board Issues
Reversed Polarity • Poor Ground • Low or High Voltage • Board Failures
Electrical faults prevent the control system from reading the sensors correctly.
Typical error causes:
- Reversed line and neutral connection
- Loose furnace ground
- Failed fuse
- Low voltage from the panel
- Faulty wiring harness
- Control board failure
Actions:
- Confirm furnace switch and breaker are on
- Ensure the blower door is fully latched
- Check the outlet or circuit for correct polarity
Technicians will verify voltage, grounding, polarity, and board integrity. Persistent electrical errors require professional repair.
Read More: How to Tell if Your Furnace Control Board Is Bad
DIY vs Professional Troubleshooting
Safe DIY checks:
- Filter replacement
- Clearing snow or debris from vent pipes
- Cleaning flame sensor
- Checking condensate lines
- Restarting the furnace to clear simple codes
Call a professional immediately if:
- Flame is sensed without a call for heat
- Rollout switch is open
- You suspect a cracked heat exchanger
- You smell gas
- Codes return after DIY steps
- Furnace locks out repeatedly
Safety components exist to prevent fire, carbon monoxide exposure, and equipment damage. Always treat safety-related codes seriously.
Furnace Maintenance for Canadian Homes
Preventing error codes is far easier than fixing them.
Follow these guidelines:
- Annual furnace maintenance by a licensed technician
- Replace filters every 60 to 90 days
- Inspect outdoor vent pipes after storms
- Keep condensate traps clear
- Clean flame sensors annually
- Follow ENERGY STAR and Technical Safety BC recommendations for safe operation
These steps keep your furnace reliable and ready through cold weather.
Need Expert Furnace Help in the North Okanagan?
If your furnace is showing an error code you cannot clear, the team at Vernon Air Conditioning, Plumbing and Electrical Services can help. Our technicians diagnose pressure switch problems, ignition failures, airflow issues, and safety faults across all major furnace brands.
Contact us today to restore your home comfort quickly and safely.
Vernon Air Conditioning, Plumbing & Electrical Services
909 Kalamalka Lake Rd, Vernon, BC V1T 6V4
Phone: 778-403-7886
Need help with Furnace Repair? Book online today for fast service across the North Okanagan.
