Bryant 315AAV Error Code 45: Control Circuitry Lockout
What Does Code 45 Mean?
Code 45 on the Bryant 315AAV is a control circuitry lockout. The integrated furnace control board has detected an internal fault in its own logic or sensing circuitry. The board will automatically attempt to reset after a 1-hour lockout period. Cycling power can also clear the lockout temporarily, but the code will repeat until the underlying cause is resolved.
The service documentation identifies three triggers: a gas valve relay stuck in a fault state, a software check error in the board's firmware, and a flame sense circuit failure. Each of these originates within the board's internal circuitry rather than in any external component, which is why the diagnostic points directly at the board as the replaceable part.
If code 45 repeats after the 1-hour auto-reset, the service documentation instructs replacing the control board. There is no field repair available for internal board faults.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Faulty furnace control board | Most common | ✗ Call a pro → |
| Gas valve relay stuck in on position | Common | ✗ Call a pro → |
| Flame sense circuit failure | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- If the code returns after the 1-hour auto-reset, the control board likely needs replacement — contact a technician
- Do not attempt to repair or modify the control board; it must be replaced as a complete unit
✓ Verified against manufacturer service manual — March 2026