Bryant 315AAV Error Code 45: Control Circuitry Lockout
What Does Code 45 Mean?
A control circuitry lockout (status code 45) on the Bryant 315AAV means the Variable Speed Furnace Control has flagged an internal fault within itself and shut down for one hour to protect the system. Bryant attributes it to a gas valve relay stuck error, a software check error, or a flame-sense circuit failure, and directs that the control be replaced if the code repeats.
This code is about the board's own integrity rather than an external component. It overlaps in theme with code 21 (gas heating lockout for a mis-wired valve or defective valve relay) and code 22 (flame proved with the valve de-energized), because a stuck valve relay or a failed flame-sense circuit inside the board can undermine the control's authority over the gas valve. The one-hour auto-reset gives a transient glitch a chance to clear, but a self-detected relay or software fault that keeps returning indicates the board itself is failing.
Because the corrective action is control-board diagnosis and, if recurring, replacement, this is exclusively a technician repair. Homeowners should not attempt to open or replace the control board.
What You'll Notice
- The furnace stops heating and does not recover for about an hour at a time
- The status LED flashes four short then five long flashes
- The lockout may clear after the one-hour auto-reset but then return, especially if the board is failing
- The furnace behaves erratically around ignition or shutdown as the internal fault surfaces
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 → |
How This Is Diagnosed
A technician first lets the one-hour auto-reset run and observes whether the code returns. A single transient event may not indicate board failure, but a repeating code 45 — consistent with a stuck gas valve relay, a software check error, or a flame-sense circuit failure that the board reports about itself — points to a defective control board. Bryant's guidance is to replace the control if the code repeats, so persistence is the key diagnostic.
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:
- Code 45 keeps returning after the one-hour auto-reset
- The furnace behaves erratically around ignition or shutdown
- You suspect a stuck gas valve relay or flame-sense circuit fault inside the board
- Any control-board diagnosis or replacement, which is exclusively a technician repair
Frequently Asked Questions
Does code 45 mean my Bryant 315AAV control board is bad?
Not necessarily on a single occurrence — the board auto-resets after an hour for a possible transient. But Bryant says to replace the control if code 45 repeats, so a recurring code points to a failing board.
Will the furnace reset itself?
Yes, code 45 auto-resets after about one hour. If the internal fault is real and persistent, however, it will lock out again and the board should be evaluated by a technician.
Sources
✓ Verified against manufacturer service manual — March 2026