Furnace control board shows error code 01 and the unit will not start a heating cycle
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.
Possible Causes
How to Fix / Troubleshooting
Safety first: Turn off power at the furnace service switch and shut off the gas supply before removing panels. Wait for all components to cool.
Error 01 on many American Standard/Trane-style integrated furnace controls indicates ignition lockout after multiple failed ignition attempts.
- Reset the control: Turn the furnace power switch OFF for 30 seconds, then ON. See if the code clears and the furnace attempts ignition.
- Inspect the flame sensor:
- Locate the flame sensor rod near the burner assembly (usually a single rod with one wire).
- Remove the mounting screw and gently pull out the sensor.
- Clean the metal rod with fine steel wool or a Scotch-Brite pad until shiny. Do not sand the porcelain.
- Reinstall and reconnect the wire firmly.
- Check the hot surface igniter (HSI):
- Visually inspect for cracks or white spots on the silicon carbide igniter.
- If damaged or not glowing during a call for heat, replace the igniter with an OEM American Standard-compatible hot surface igniter.
- Verify gas supply:
- Ensure the manual gas shutoff valve to the furnace is fully open.
- If other gas appliances are weak or not working, contact your gas supplier.
- If lockouts continue: The gas valve, burner orifices, or control board may be faulty. At this point, contact a qualified HVAC technician for gas pressure testing and combustion analysis.