Carrier 59SC2B Error Code 22: Abnormal Flame-Proving Signal
What Does Code 22 Mean?
Status code 22 on the Carrier 59SC2B means the flame sensor is detecting a flame while the gas valve is de-energized. When the gas valve is off, no gas should be flowing and no flame should be present. The furnace keeps the inducer motor running continuously when this fault is active to vent any gas that may be leaking through.
This condition almost always indicates a gas valve that has failed internally — either leaking past the valve seat or stuck in the open position. Gas valves contain internal seals that can degrade over time, especially in furnaces that have been in service for many years. A stuck-open valve is a more acute failure where the valve mechanism physically cannot close.
This is one of the most urgent furnace fault codes because uncontrolled gas flow poses a safety risk. If you see this code, turn off the gas supply to the furnace using the manual gas shutoff valve, then turn off furnace power. Do not attempt to restart the furnace. Contact an HVAC technician to inspect 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 — turn off gas supply and furnace power, then call a technician for gas valve inspection and replacement
✓ Verified against manufacturer service manual — March 2026