Bryant 340MAV Error Code 22: Abnormal Flame-Proving Signal
What Does Code 22 Mean?
Status code 22 on the Bryant 340MAV is an abnormal flame-proving signal fault. The Carrier integrated furnace control has detected that the flame sensor is proving a flame while the gas valve is de-energized and should be closed. When this fault is active, the inducer motor continues running to ventilate the heat exchanger until the fault is cleared.
The service documentation identifies a leaky gas valve as the cause. A leaky valve allows a small amount of gas to pass through its seat even when the valve is commanded off, sustaining a residual flame that the flame sensor detects. This is a mechanical wear issue in the valve itself.
Because this fault indicates gas is flowing when it should not be, it is a safety-relevant condition and the opposite failure mode from code 34, where the control cannot detect a flame that is present. Do not continue operating the furnace until a licensed HVAC technician has inspected and, if necessary, replaced the gas valve.
What You'll Notice
- The inducer motor keeps running even after the thermostat is satisfied and no heat is being called for
- The furnace behaves as though it cannot fully shut down between or after cycles
- You may see a residual or lingering flame at the burners when the furnace should be off
- The fault persists until power is cut, and returns when the valve passes gas again
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Leaky gas valve | Most common | ✗ Call a pro → |
How This Is Diagnosed
A technician verifies that the flame signal is present while the gas valve is de-energized, which points to gas passing through a valve that should be closed. The valve is checked for seat leakage and, if confirmed, replaced. The flame sensor and its wiring are also verified to rule out a false flame signal, but a genuine sustained flame with the valve commanded off indicates the valve itself.
When to Call a Professional
This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:
- The inducer keeps running with no call for heat, or you see a flame after the furnace should be off
- You smell gas — leave the home first and call your gas company
- The code returns after any reset attempt
- Do not keep operating the furnace until the gas valve has been inspected
Frequently Asked Questions
Why does my furnace inducer keep running after it shuts off?
On code 22 the control keeps the inducer running to purge combustion gases because it still detects a flame with the gas valve commanded off — usually a leaking gas valve. This needs prompt professional service.
Is code 22 an emergency?
Treat it seriously. It means gas may be burning when it should not be. Shut the furnace off, and if you ever smell gas, leave and call your gas company, then have a technician inspect the valve.
✓ Verified against manufacturer service manual — March 2026