Seeing a code like 45 on your furnace? Fault codes are how the board reports a problem; they are not a repair instruction. This page explains how the codes work, why we will not hand you one fixed meaning for code 45, the safe first steps, and when furnace faults need a technician.
How furnace fault codes work
Nearly every modern gas furnace shows faults as a flashing LED on the control board behind the lower access panel. You count the flash pattern — for example a number of short blinks, or a slow/fast rhythm — and match it to the legend printed on the inside of the panel door or in the model’s installation manual. A furnace that locks out has shut the burners down on purpose for safety; the code is the board explaining why it stopped.
Why we will not give you one fixed meaning for code 45
Fault-code numbers are not standardized. The same number can mean different things across furnace model years and product lines, and the cheap error-code lists floating around the web (older versions of pages like this one included) frequently contradict each other. We would rather be useful than confidently wrong about a gas appliance. The three sources that are actually reliable for your unit are:
- the legend printed on the unit — inside the furnace panel door, on the boiler casing, or in the outdoor-unit service flap;
- the model-specific installation or service manual (search your exact model number, not just the brand); and
- a licensed technician reading the code on-site, who can confirm it against live measurements instead of guessing.
Safe first steps before you call
Work through these in order. If the code clears and stays gone, great — if it returns, the board is telling you there is a real fault to fix.
- Set the thermostat to Heat and a few degrees above room temperature.
- Make sure the furnace switch (it looks like a light switch nearby) and the breaker are on.
- Check that the lower access panel is fully seated — a furnace will not fire if the door safety switch is not pressed in.
- Replace a dirty 1-inch filter; a clogged filter overheats the furnace and trips the limit switch.
- Confirm the gas is on, then try one power-cycle: off at the switch for 30 seconds, back on. If it fires and then faults again, stop and call.
Safety first — when to stop and get help
If you smell gas (a rotten-egg odour) or hear hissing near the appliance, do not touch switches or relight anything. Leave the building and call FortisBC’s gas-emergency line (the number is on your gas bill and at fortisbc.com) from a safe spot, then call us. If anyone feels dizzy, nauseous or has a headache that eases when they go outside — possible carbon monoxide — get everyone out and call 911. Never bypass a furnace door switch, flame sensor, or pressure-switch safety to force the system to run.
When to call HeatLand
If the fault keeps coming back, the system is in a hard lockout, or the code involves ignition, the gas valve, the heat exchanger, a pressure switch or anything you cannot safely reach, it is time for a licensed technician. HeatLand installs, repairs and maintains furnaces across Vancouver, Burnaby and the Lower Mainland. We will read the code on-site, confirm the real cause, and quote the fix before any work — no pressure.
Furnace showing a fault code in Metro Vancouver?
Get an honest diagnosis from a licensed local technician.
Frequently asked questions
Can I clear code 45 on my furnace myself?
You can safely try the basic checks above and a single power-cycle or reset. If the code returns, the furnace is reporting a genuine fault that needs diagnosis — do not keep resetting a locked-out gas appliance.
Does code 45 mean my furnace needs to be replaced?
Usually not. Most fault codes trace back to a sensor, igniter, pressure switch, capacitor or wiring issue that a technician can repair. A code is rarely a verdict on the whole system.
Is it safe to keep running the furnace with a fault showing?
If it has gone into a hard lockout, it has shut itself down for a reason — leave it off and have it checked rather than forcing it to run. Bypassing a safety to keep heat or cooling on is never worth the risk.
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