Carrier Furnace Error Codes — Complete Guide

Carrier furnaces — along with sister brands Bryant and Payne — use a 2-digit LED flash code system. Count short flashes first, then long flashes (e.g., 3 short + 3 long = code 33). Also covers Bryant, Payne.

All Carrier Error Codes

Code 14 (1 short + 4 long flashes)

Carrier Code 14 — Furnace Heating Lockout

Locked out after exhausting heating retry attempts.

Code 21 (2 short + 1 long flashes)

Carrier Code 21 — Gas Heating Lockout

Gas heating lockout — won't auto-reset, requires power cycle.

Code 22 (2 short + 2 long flashes)

Carrier Code 22 — Abnormal Flame Proving Signal

Flame detected when gas valve is supposed to be closed — leaky valve.

Code 23 (2 short + 3 long flashes)

Carrier Code 23 — Pressure Switch Didn't Open

Pressure switch did not open — stuck switch or tubing obstruction.

Code 24 (2 short + 4 long flashes)

Carrier Code 24 — Secondary Voltage Fuse Open

Secondary voltage fuse blown — short in 24V control wiring.

Code 31 (3 short + 1 long flashes)

Carrier Code 31 — Pressure Switch Did Not Close

Pressure switch did not close — blocked vent, bad inducer, or stuck switch.

Code 33 (3 short + 3 long flashes)

Carrier Code 33 — Limit or Flame Rollout Switch Open

Limit or flame rollout switch open — usually restricted airflow.

Code 34 (3 short + 4 long flashes)

Carrier Code 34 — Ignition Proving Failure

Ignition proving failure — flame sensor, igniter, or gas supply issue.

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If you don't see your code here, try our master error code lookup covering all major brands, or our symptom-based diagnostic tool.

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Carrier Furnace Error Codes — Complete Guide

All Carrier Error Codes

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