Guardian opener LED shows code “8”, door reverses randomly or stops at inconsistent positions.

Safety first: Keep people and pets clear of the door while performing travel calibration. Disconnect power before handling internal wiring.

• Reset travel limits: Follow the Guardian manual to erase and reprogram open/close limits. Typically this involves holding the “Set” or “Program” button until the LED flashes, then running the door to full open and full close positions.
• Check rail sensor (if equipped): Some Guardian models use a magnetic or optical encoder on the rail or motor shaft. Inspect the sensor and wiring harness for damage or loose connections.
• Secure wiring: Ensure the encoder or travel sensor wires are firmly seated in the logic board connector and not pinched by the opener cover.
• Test multiple cycles: After recalibration, run the door through at least 5 full open/close cycles to confirm consistent stopping points and that the code clears.
• Replace encoder or logic board: If the opener cannot retain limits or continues to misread position, replace the encoder module (if separate) or the Guardian logic board.