LiftMaster / Chamberlain / Craftsman · Garage Door Opener error code

4-6Sensors misaligned or briefly blocked

Cross-checked Power off, standard tools

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Related diagnostic guides

Guide · Garage Door Opener

Garage door reverses or will not close (safety sensors)

Nearly always the photo-eye safety sensors: blocked, misaligned, sun-blinded or miswired. Sensors must be repaired, never bypassed. If sensors are fine, look at force/limits and door binding.

5 steps ~30 mineasy

Install · Garage Door Opener

Garage door opener install (spring work BLOCKED)

An opener only moves a door that is already balanced by its springs. Check balance first, mount the rail and header bracket per the manual, place the safety reversing sensors no higher than 6 in above the floor and aligned, and test the auto-reverse. Spring and cable work is BLOCKED: refer to a garage door technician.

7 steps ~240 minmoderate