Carrier Furnace Error Codes & Fix Guides
All FixCode Guide coverage for Carrier furnace error codes: start with the complete code list, or jump to a deep-dive guide for a specific code. Everything is verified against Carrier manufacturer documentation.
Guides in this section
Carrier Furnace Status & LED Codes: Solid, Blinking, Yellow & Orange LightsCarrier Furnace 33 Error Code: Meaning, Causes & FixCarrier Furnace Error Codes List: Every Code ExplainedCarrier Furnace 13 Error Code: Meaning, Causes & FixCarrier Furnace 24 Error Code: Meaning, Causes & FixCarrier Furnace 31 Error Code: Meaning, Causes & FixCarrier Furnace 32 Error Code: Meaning, Causes & FixCarrier Furnace 14 Error Code: Meaning, Causes & FixCarrier Furnace 12 Error Code: Meaning, Causes & FixCarrier Furnace 21 Error Code: Meaning, Causes & FixCarrier Furnace 43 Error Code: Meaning, Causes & Fix
Most searched Carrier furnace codes
| Code | Meaning |
|---|---|
| 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 |
| 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. |
| 14 | 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) |
| 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. |
| 24 | Secondary voltage fuse open — the 3-amp fuse on the control board has blown (24V circuit short/overload). |
| 31 | Pressure switch did not close (or opened) during operation — the inducer couldn't prove proper venting draft. |
| 32 | Low heat pressure switch did not close / opened (on two-stage Carrier furnaces: the low-fire pressure switch proof failed). |
| 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. |
| 43 | Low-heat pressure switch open while the high-heat pressure switch is closed — the stage switches disagree. That is the mainstream Carrier chart's wording (58CVA service label: 'LOW-HEAT PRESSURE SWITCH OPEN WHILE HIGH-HEAT PRESSURE SWITCH IS CLOSED'). On the older 58MVP variable-speed generation the same code is titled PRESSURE SWITCH CALIBRATION FAULT — see the honesty note in the what and FAQ: both titles are Carrier's own, on different generations. |