Payne Furnace Code 21
Hard lockoutShown as: 2 short flashes, 1 long flash
Gas heating lockout. 24 VAC was sensed on the gas valve when it should not be there. The control turns off power and waits 5 minutes before retrying.
Manual wording: “21 GAS HEATING LOCKOUT - Turn off power and wait 5 minutes to retry. Check for: - Stuck closed gas valve relay on control. - Miswire or short to gas valve wire.”
Documented for: PG92ESA, PG95ESA, PG96VTA, PG80MSU
Likely causes, most common first
- Stuck-closed gas valve relay on the control board
- Miswire or short to the gas valve wire
When to call a technician
This code means the board may not be able to keep the gas valve shut. Turn the furnace off at the service switch and call a technician.
A Payne furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- PG92ESA: Installation, Start-up, Operating and Service and Maintenance Instructions (Payne, PG92ESA multipoise 92% single-stage condensing gas furnace) · checked 2026-08-25
- PG95ESA: Installation, Start-up, Operating and Service and Maintenance Instructions (Payne, PG95ESA multipoise 95% single-stage condensing gas furnace) · checked 2026-08-25
- PG96VTA: Installation, Start-up, Operating and Service and Maintenance Instructions (Payne, PG96VTA two-stage, variable-speed ECM 4-way multipoise condensing gas furnace) · checked 2026-08-25
- PG80MSU: Installation, Start-up, Operating and Service and Maintenance Instructions (Payne, PG80MSU 80% multipoise gas furnace with 3-digit display and pressure transducer) · checked 2026-08-25