Updated 2026-06-25

Carrier Furnace Code 13: What It Means & How to Fix It

Compiled & reviewed by Nikolai Tsyrenov · Updated 2026-06-25 · confidence: high

What does Carrier furnace code 13 mean?

Limit circuit lockout — the lockout version of code 33, triggered when the limit or flame-rollout switch stays open too long. Most often caused by The limit or flame-rollout switch stayed open longer than 3 minutes.

What Carrier furnace code 13 means

Limit circuit lockout — the lockout version of code 33, triggered when the limit or flame-rollout switch stays open too long.

Common causes

Homeowner-safe steps to try

  1. Turn the thermostat OFF and check the air filter — replace it if dirty (the most common cause of overheating)
  2. Make sure supply registers and return-air grilles are open and unblocked, and remove anything on or near them
  3. Cycle power at the furnace switch (off, wait, on); the control also auto-resets after about 3 hours
  4. Do NOT press or bypass any rollout or limit switch — a tripped flame-rollout switch indicates a combustion safety problem

When to call a licensed HVAC technician

If the basic checks below don't clear the code, the fault recurs, or anything involves the gas valve, burners, flame sensor or wiring, stop and book a licensed HVAC technician. Repairs to the combustion or gas system are not DIY.

⚠️ Safety first. Gas furnaces burn fuel and produce combustion gases. If you ever smell gas (a rotten-egg or sulfur odor), hear hissing, or your carbon-monoxide alarm sounds, do not touch light switches, thermostats, or the furnace — leave the home immediately and call your gas utility's emergency line or 911 from outside. Homeowners should limit themselves to simple, safe steps: setting the thermostat, checking and replacing the air filter, confirming the furnace switch and breaker are on, keeping supply registers and return grilles open, and clearing snow, ice, or debris from outdoor vent and intake terminations. Never bypass, jumper, or reset safety switches (limit, flame-rollout, or pressure switches), never open the gas valve or burner compartment, and never attempt combustion, electrical, or control-board repairs yourself. Error codes point toward a problem but are not a substitute for proper diagnosis — when in doubt, turn the system off and call a licensed HVAC technician. Keep working carbon-monoxide detectors on every level of your home.
When to call a pro: Call a licensed HVAC technician if the code returns after replacing the filter and clearing airflow restrictions, or if a flame-rollout switch has tripped (these require manual reset by a pro and can signal a heat-exchanger or venting hazard).

Carrier furnace code 13 FAQ

What does Carrier furnace code 13 mean?
Limit circuit lockout — the lockout version of code 33, triggered when the limit or flame-rollout switch stays open too long.
What causes Carrier furnace code 13?
Common causes: The limit or flame-rollout switch stayed open longer than 3 minutes; 10 successive limit trips during high-heat operation; Persistent overheating from severely restricted airflow (very dirty filter, closed/blocked vents, blocked return); A failed blower motor or a stuck-open limit switch.
Can I fix Carrier furnace code 13 myself?
You can safely try: Turn the thermostat OFF and check the air filter — replace it if dirty (the most common cause of overheating); Make sure supply registers and return-air grilles are open and unblocked, and remove anything on or near them; Cycle power at the furnace switch (off, wait, on); the control also auto-resets after about 3 hours; Do NOT press or bypass any rollout or limit switch — a tripped flame-rollout switch indicates a combustion safety problem. Call a licensed HVAC technician if the code returns after replacing the filter and clearing airflow restrictions, or if a flame-rollout switch has tripped (these require manual reset by a pro and can signal a heat-exchanger or venting hazard).

Other Carrier furnace codes

Carrier Code 11No previous code stored — the control has no fCarrier Code 12Blower on after power up — the blower runs forCarrier Code 24Secondary-voltage fuse is open — the 3-amp conCarrier Code 25Model-selection or setup error — the control bCarrier Code 31Pressure switch or relay did not close, or reoCarrier Code 32Low-heat pressure switch did not close, or reoCarrier Code 33Limit circuit fault — the high-limit or flame-Carrier Code 34Ignition-proving fault — flame was not sensed,

All Carrier furnace codes →

Sources: shareddocs.com · manualslib.com. General information for homeowners, not professional advice — confirm against your furnace's manual and a licensed technician.