Quick answer
Code 14 on a Carrier furnace is an ignition lockout: the furnace failed to light the gas or prove flame in four attempts, so the control stopped trying. It resets itself after 3 hours, or sooner if power is cycled. Check that the gas supply is on, cycle power once, and book a diagnosis if it locks out a second time.
A Carrier furnace showing code 14 has tried to light four times, failed to ignite the gas or prove a flame each time, and locked itself out. Carrier calls it ignition lockout, and the control clears it automatically after 3 hours. On the status light it reads as one short flash and four long. The furnace is not damaged by the lockout; it is waiting, with the gas valve closed, for the timer or for someone to cycle the power.
Code 14 is the lockout; code 34 is the fault behind it
Every code 14 starts as a code 34, which is the ignition proving failure itself. The control retries, and when the last attempt fails it replaces 34 with 14 and starts the 3-hour clock. Whatever stopped the flame from being lit or sensed is still there when the clock runs out. That is why some furnaces heat for a while after a reset and then go cold again a few hours later.
Carrier builds more than one control board, and the code list is not identical on every one. Read the label on the inside of the furnace door before acting on any list, this one included.
How long can you leave a furnace in code 14?
A locked-out furnace is safe; a house without heat is the risk. With no action the furnace stays off for 3 hours, tries again, and if the fault remains, locks out for another 3. In mild weather that is an inconvenience. In a January cold snap, a house can lose enough heat over a night of repeated lockouts to put plumbing on outside walls at risk, and the steps in how to keep pipes from freezing if the furnace fails are worth starting early.
The decision rule is one lockout, one reset. If the furnace lights and runs normally afterward, watch it. If code 14 returns, stop resetting and call.
What to check before you cycle the power
- Is the gas on? The shut-off on the pipe beside the furnace should have its handle parallel to the pipe.
- Do the other gas appliances work? Light a range burner or check the water heater. If nothing in the house has gas, the problem is at the meter and the call is to Enbridge Gas.
- Has anything changed? A gas meter swap, a new appliance or basement work can leave a valve closed or air in the line.
- Then turn the furnace switch off, wait a minute and turn it back on. That clears the lockout once.
Watch the next start through the sight glass if your door has one. Whether the igniter glows, whether the burners light, and how many seconds the flame lasts are the three things a technician will ask about.
What usually causes an ignition lockout
- A dirty flame sensor. The burners light, the sensor cannot confirm it, and the control shuts the gas after a few seconds. The most common cause by a wide margin.
- A failed hot surface igniter. No glow means no flame, and four silent tries end in lockout.
- Low gas pressure or a closed gas valve. The igniter glows and nothing lights; see why a furnace igniter glows but does not light.
- A grounding fault. Flame sensing depends on a solid ground between the burners, the cabinet and the control, and a loose or corroded ground wire makes a good flame invisible to the board.
What the repair involves and what it costs in Ontario
A technician reproduces the failure and watches the sequence: inducer, pressure switch, igniter, gas valve, flame, flame signal. Where the sequence stops tells them which part to test. Opening the burner compartment, cleaning or replacing the sensor and measuring gas pressure are gas-side tasks, which in Ontario means a TSSA-licensed gas technician.
- Flame sensor cleaning or replacement: $150–$300.
- Hot surface igniter: $200–$450.
- Gas valve: $500–$1,000.
- Diagnostic visit: $90–$150, applied to the repair when you go ahead.
ZK Mechanical runs a 24/7 emergency line with no after-hours surcharge, which matters when code 14 shows up on a cold night. See furnace repair for how a visit works, the Carrier furnace error code guide for the rest of the list, or contact us with the model number and the code you saw. The number is (647) 801-1252.