51
Carrier
Gas Valve Relay Fault
Furnace LED shows code 51 (gas valve relay fault). Furnace will not open gas valve; no flame.
Advertisements
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Advertisements
Possible Causes
Failed gas valve relay on control board, shorted gas valve coil, miswired gas valve harness
How to Fix / Troubleshooting
Safety first: Turn off power and gas. Do not attempt to bypass gas safety controls.
- Inspect gas valve wiring: Verify that the two wires to the gas valve are firmly connected and not pinched or damaged.
- Check for previous shorts: Look for signs of melted insulation or arcing near the gas valve and harness.
- Reset power: Turn power off for 30 seconds, then back on and call for heat. If the code 51 returns immediately, the board relay or gas valve may be defective.
Testing gas valve coils and board relays requires electrical measurements and gas safety knowledge; have a licensed technician perform this repair.
Advertisements
Repair Difficulty
Professional Required
5/5
Advertisements