Carrier Furnace 14 Error Code: Meaning, Causes & Fix
Ignition lockout — the furnace failed to ignite gas and prove flame in 4 attempts, so the control locked out; it auto-resets after 3 hours (Carrier's wording; see code 34 for the underlying ignition-proving fault)
14 is the lockout that follows code 34 ignition-proving failures: the control ran its trial-for-ignition sequence (inducer, igniter, gas valve, flame proof) four times without establishing and proving flame, and shut down for safety. Carrier's variable-speed guide adds a second route into the same lockout: if the inducer motor is running at full speed during the lockout, flame sense was lost three times within 60 minutes of cumulative gas-valve operating time after the valve had already been on for 70 seconds — a pattern Carrier says is usually caused by flame rollout disturbing flame sense before the rollout switch can trip, which is licensed-technician territory, not a cleaning job. In the common case, though, the failure inside those trials is the real fault — a dirty flame sensor (burners light, then drop), a failed hot-surface igniter (burners never light), or gas not reaching the burners. 14 tells you the trials happened and failed; watching one trial tells you why.
What causes the 14 code on a Carrier furnace?
Dirty flame sensor
If the burners light then cut within seconds, the sensor's oxide coat is the classic cause — the commonest ignition fault in all furnaces. Carrier's own troubleshooting flow for this fault ends at the sensor: check the flame-sensor current, clean the sensor, and recheck.
Failed hot surface igniter
If it never lights at all: the igniter (a fragile ceramic element) has cracked or opened — among the most replaced parts on any furnace.
No gas to the furnace
A closed gas cock, a meter or supply problem, or other gas appliances also out (the stove test tells you). Carrier's code 34 check list starts with the gas valve turned off and the manual shut-off valve.
Dirty burners, poor carryover or low gas pressure
Ignition is ragged and trials time out — Carrier lists inadequate flame carryover, low inlet gas pressure and inadequate combustion air on the code 34 chart; all are technician measurement territory.
Flame lost after proving (variable-speed models)
The 58MVC route above: flame proved, ran, then sense was lost repeatedly — Carrier links it to flame rollout disturbing the sensor, which is why this branch goes straight to a technician.
Checks to run before you replace anything
- SAFETY: repeated ignition trials with a raw gas smell = stop, ventilate, leave and call the gas utility or a professional. Do not keep cycling the furnace.
- Watch one trial through the sight glass: igniter glows? Burners light? Light-then-die within seconds = flame sensor side. No glow and no light = igniter or its power.
- Note whether the inducer runs at full speed during the lockout itself — on variable-speed Carrier models that detail separates the ordinary failed-ignition case from the flame-loss/rollout case a technician needs to hear about.
- Check the furnace gas cock is open and other gas appliances work.
How to fix the 14 error code
- Clean the flame sensor if light-then-die is the pattern: power off, remove the sensor, and polish the rod gently — Carrier's flow specifies cleaning the flame sensor (its chart uses fine sandpaper/steel wool on the rod); the goal is removing the oxide sheen, not scoring metal.
- Replace the igniter if it does not glow (handle the new one by its base — skin oils damage hot-surface igniters; never touch the element).
- Gas pressure, burner, carryover and combustion-air findings are technician work with a manometer — and the flame-loss variant of this lockout is technician work from the first observation.
The part that usually fails: Flame sensor (clean first) or hot surface igniter
The two highest-probability parts in furnace ignition repair. Observation of one trial — glow? light? die? — picks between them reliably. Carrier's technician flow measures flame-sensor current in DC microamps (its chart calls below 0.5 abnormal and roughly 4.0-6.0 nominal), which is meter work for a professional, not an owner check.
Carrier furnace error code 14 reset button
Carrier states the control will auto-reset after 3 hours. A power cycle also clears the lockout, but only reset after you have observed or fixed the trial failure — resetting a furnace that still cannot prove flame just runs four more failed trials and re-locks, and repeated raw-gas trials are a safety problem, not a strategy.
Carrier fault codes are stored by the control board and shown as two-digit codes via the status LED (short flash = first digit, long flash = second digit, with a pause between). Most codes clear automatically once the fault condition is gone and a new call for heat succeeds; a hard lockout (such as code 13 or 14) needs the fault fixed, then power cycled at the furnace switch or breaker for a few seconds, and in some lockouts the board waits up to an hour or requires several successful cycles before normal operation resumes. Clearing a lockout without fixing its cause just restarts the countdown to the next lockout.
Why does the 14 code keep coming back?
14 returning within weeks of a sensor clean means the sensor is genuinely failing or combustion is dirtying it fast (burner/combustion check). Returning after an igniter change suggests gas pressure or valve issues. Returning with the inducer running hard during lockout points at the flame-loss branch — book the technician and describe exactly that.
How to stop 14 coming back
- Dirty flame sensor: If the burners light then cut within seconds, the sensor's oxide coat is the classic cause — the commonest ignition fault in all furnaces. Carrier's own troubleshooting flow for this fault ends at the sensor: check the flame-sensor current, clean the sensor, and recheck.
- Failed hot surface igniter: If it never lights at all: the igniter (a fragile ceramic element) has cracked or opened — among the most replaced parts on any furnace.
- No gas to the furnace: A closed gas cock, a meter or supply problem, or other gas appliances also out (the stove test tells you). Carrier's code 34 check list starts with the gas valve turned off and the manual shut-off valve.
Retrieving stored fault codes on Carrier furnaces
Carrier boards include a component test mode (a test pin/shorting jumper on the board, per the installation manual) that runs the inducer, blower and ignition sequence on demand, and the board keeps the last faults in memory readable as LED codes. The full fault chart is printed on the blower-door label of every unit — photograph it before relying on any online chart, because code assignments differ slightly between board generations.
Other Carrier furnace error codes
| Code | Meaning | First fix |
|---|---|---|
| 11 | No previous code — the control's stored fault history is empty; this is not a fault | No repair needed: run a heating or cooling cycle to check the system; a furnace flashing 11 simply has nothing stored |
| 12 | Depends on the generation — read this before assuming either way. On most Carrier furnaces: 'blower on after power up', a normal start-up behaviour (blower runs about 90 seconds when power returns during a heat call), not a fault. On the variable-speed 58MVP generation the same digits are a real fault: 'blower calibration lockout' — the blower's calculated low-heat speed fell outside 250-1300 RPM on two successive attempts; auto-reset after 3 hours | Mainstream 12: nothing — if heating follows, the code was information about a power interruption, not a failure. |
| 13 | Limit circuit lockout — the control locked the furnace out because a limit or flame rollout switch in the limit circuit stayed open longer than 3 minutes, or limit trips came in succession (10 successive trips during high-heat; the variable-speed generation also locks out after 3 successive trips during low-heat). The control auto-resets after 3 hours. | Restore airflow: new filter, open registers, clean the blower wheel (and have the indoor coil cleaned if it's matted — HVAC technician work). |
| 15 | Blower motor lockout — the blower failed to reach 250 RPM or to communicate within 30 seconds of turn-on, in two successive heating cycles | The control auto-resets after 3 hours; diagnose as code 41 — licensed HVAC technician work |
| 21 | Gas heating lockout — Carrier's service label words it: 'STATUS CODE 21 — GAS HEATING LOCKOUT. Control will NOT auto reset. Check for: mis-wired gas valve; defective control (valve relay).' The control has shut down gas heating and, uniquely among Carrier's common lockouts, it will not clear itself with time. | The one owner-level step Carrier sanctions: turn power off, wait 5 minutes, restore power and set the thermostat to call for heat once. If 21 does not return and the furnace completes a normal heating cycle, the lockout is cleared. If it returns, stop — the remaining steps are licensed-technician work. |
| 22 | Abnormal flame-proving signal — flame is proved while the gas valve is de-energised; the inducer runs until the fault clears | Turn the furnace off and do not run it on this code; a leaking gas valve is licensed HVAC technician work |
| 23 | Pressure switch did not open — a pressure switch is still closed (made) when a call for heat begins | Check the pressure tubing for blockage and clear it; switch testing is licensed HVAC technician work — never jumper the switch |
| 24 | Secondary voltage fuse open — the 3-amp fuse on the control board has blown (24V circuit short/overload). | Repair the short (tape/replace damaged wire sections, correct rub points with a grommet). |
| 25 | Invalid model selection or setup error — the model plug is missing or incorrect, or a setup switch is wrongly set | Four flashes at power-up only: the control defaults to its stored model and still runs; correction is licensed technician work |
| 31 | Pressure switch did not close (or opened) during operation — the inducer couldn't prove proper venting draft. | Clear vent/intake obstructions; correct a sagging vent run so condensate drains back as designed. |
| 32 | Low heat pressure switch did not close / opened (on two-stage Carrier furnaces: the low-fire pressure switch proof failed). | Clear restrictions; clean condensate path; replace bad tubing. |
| 33 | Limit circuit fault — a limit, flame rollout, draft safeguard or blocked-vent switch (as fitted) in the limit circuit is open right now, but the control hasn't escalated to lockout (13) yet. | Restore airflow (filter, registers, wheel/coil cleaning). |
| 34 | Ignition proving failure — flame was not sensed in the trial for ignition; the control tries 3 more times, then lockout code 14 | Confirm gas and the manual valve are on; the rest is licensed HVAC technician work |
| 35 | Gas valve fault (modulating models) — the modulating gas valve failed to respond to a control command, or power to its electronics was interrupted | Gas valve and wiring diagnosis is licensed HVAC technician work |
See the full list on the Carrier Furnace error codes hub.
Codes 14 gets confused with
12 — Depends on the generation — read this before assuming either way. On most Carrier furnaces: 'blower on after power up', a normal start-up behaviour (blower runs about 90 seconds when power returns during a heat call), not a fault. On the variable-speed 58MVP generation the same digits are a real fault: 'blower calibration lockout' — the blower's calculated low-heat speed fell outside 250-1300 RPM on two successive attempts; auto-reset after 3 hours Carrier uses the number 12 for two unrelated things, and the model generation decides which one your furnace means.
13 — Limit circuit lockout — the control locked the furnace out because a limit or flame rollout switch in the limit circuit stayed open longer than 3 minutes, or limit trips came in succession (10 successive trips during high-heat; the variable-speed generation also locks out after 3 successive trips during low-heat). The control auto-resets after 3 hours. Carrier code 13 is a lockout, not a first offence, and Carrier defines its triggers exactly: a limit or flame rollout switch (on some models also a draft safeguard or blocked vent switch in the same circuit) open longer than 3 minutes, or successive limit trips — 10 during high-heat, and on the variable-speed generation 3 during low-heat.
21 — Gas heating lockout — Carrier's service label words it: 'STATUS CODE 21 — GAS HEATING LOCKOUT. Control will NOT auto reset. Check for: mis-wired gas valve; defective control (valve relay).' The control has shut down gas heating and, uniquely among Carrier's common lockouts, it will not clear itself with time. Code 21 is the Carrier control declaring that it cannot trust its own gas valve output.
31 — Pressure switch did not close (or opened) during operation — the inducer couldn't prove proper venting draft. Before Carrier furnaces light, the inducer fan runs and the pressure switch must close to prove the vent is drafting.
Frequently asked questions
How many times does a Carrier furnace try to ignite before code 14?
Four. Carrier's chart defines code 14 as the system having failed to ignite gas and prove flame in 4 attempts (the code 34 sequence repeats the ignition trial three more times after the first failure before lockout). After lockout the control auto-resets in 3 hours and tries again — which is why a furnace with a dead igniter can be found cycling through lockouts all day.
How do I know if it's the igniter or the flame sensor?
Watch a trial: no glow = igniter side. Glow, flame, then flame dies in seconds = flame sensor side. That short observation is the whole first diagnosis.
Can I clean a flame sensor with sandpaper?
Carrier's own troubleshooting flow says to clean the flame sensor and recheck its current; owners who clean the rod should use a fine abrasive pad or fine sandpaper gently — the goal is removing the oxide sheen, not metal. Aggressive sanding scores the rod and shortens its life.
Related guides
Facts on this page were checked against manufacturer documentation: mans.io · mans.io · www.shareddocs.com · mans.io · www.manualshelf.com · manualsdump.com