Start With the Sensor Symptom
A garage door that reverses, refuses to close or shows a blinking sensor light can have alignment, wiring or device problems.
Before replacing parts, check whether the sensors are physically blocked, knocked out of alignment or visibly damaged. The opener model also matters because replacement sensors need to be compatible with the control system.
Alignment, Mounting and Existing Wiring
Sensors need to face one another across the door opening at the intended height. Loose brackets or accidental impact can move them enough to interrupt the safety beam.
Existing low-voltage wiring should remain intact and protected. If wiring is damaged inside walls or the opener control board is failing, the repair can move beyond a simple sensor replacement.
Sensor Repair vs Opener or Door Repair
A working sensor system cannot correct a mechanically binding door or a failed opener motor. Those problems belong to Garage Door Installation & Repair or Garage Door Opener Installation. Sensor work is limited to compatible hardware, alignment and accessible sensor wiring at the door opening.