Control board displays Er10 and furnace will not respond to keypad inputs.

Safety first: Disconnect power before removing the control panel or accessing the control board.

Steps:

• 1. Power cycle: Unplug the furnace for 5–10 minutes, then plug it back in. If Er10 remains, continue.
• 2. Access the control panel: Remove the screws securing the front control panel or bezel to expose the keypad and control board.
• 3. Inspect the ribbon cable: Ensure the flat ribbon cable or harness between the keypad and control board is fully seated and not damaged. Reseat both ends.
• 4. Check for moisture or corrosion: Look for signs of water, condensation, or corrosion on the keypad and board. Dry gently with a soft cloth; do not use heat guns.
• 5. Test keypad buttons: With the panel reconnected and power restored, test each button. If some or all buttons do not respond and Er10 persists, the keypad assembly may be defective.
• 6. Replace keypad or control board: Replace the user interface/keypad assembly first, as it is usually less expensive. If the problem continues, the main control board may need replacement by a qualified technician.