DIAGNOSIS: This is the travel limit error code. The opener thinks the door didn't complete its full open or close cycle. Usually a sensor alignment or obstruction issue.
FIX: Check the path of the door for any physical blockage first. Then, inspect the safety reversing sensors (the small black boxes near the floor on each side of the door). Ensure their lenses are clean and the amber/green indicator lights are solid, not blinking. Realign them so they face each other directly.
IF THAT DIDN'T WORK: The internal travel limit settings may have drifted. Re-teach the travel limits. Press and hold the black 'Learn' button on the motor unit for 6 seconds until the light blinks. Use your wall console to open and close the door fully once to reset the limits.
HEADS UP: Never try to adjust mechanical limit screws on this model. All limits are set electronically via the learn button. Forcing the door with a travel error can burn out the motor.