Carrier 59SC5A Error Code 22: Abnormal Flame-Proving Signal
What Does Code 22 Mean?
Status code 22 on the Carrier 59SC5A means the flame sensor is detecting a flame while the gas valve is de-energized. No flame should be present when the gas valve is closed. The furnace responds by running the inducer motor continuously to vent any gas leaking past the valve until the condition clears.
This fault indicates a gas valve that is either leaking internally or mechanically stuck open. Internal leaks occur when the valve seat deteriorates over time, allowing a small but dangerous amount of gas to seep through to the burners. A stuck-open valve is a more complete mechanical failure where the valve cannot close at all.
This is among the most serious fault codes a furnace can display. If you see status code 22, immediately shut off the gas supply using the manual shutoff valve on the gas line feeding the furnace, then turn off furnace power at the breaker or disconnect switch. Do not attempt to restart the furnace. Call an HVAC technician to test and replace the gas valve.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Leaky gas valve | Common | ✗ Call a pro → |
| Stuck-open gas valve | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Immediately — shut off gas and power, then call a technician to replace the gas valve
✓ Verified against manufacturer service manual — March 2026