Garage door one sensor light is off completely
This is almost always a broken sensor wiring, or a failed sensor. Repair costs $125 to $300 and takes 30 to 45 minutes. Safe to operate: Yes, it will not close unattended.
Check this first — it may cost you nothing
Follow the wire from the dark sensor back toward the opener, looking for a staple through it or a break where it turns a corner. That is the usual cause and it is inexpensive.
Why this happens
A dark sensor is not misaligned — it is not receiving power. Misalignment makes a light blink or change colour; no light at all points at the wiring between the sensor and the opener, or at a dead sensor.
Each sensor should show a steady light. A dark or flickering receiver means the beam is broken — wipe the lenses and re-aim before calling anyone.
Less likely, but possible
- A staple driven through the wire during installation, failing years later
- A sensor destroyed by water on a flooded floor
- A failed terminal on the opener itself
What happens if I ignore it?
The door will not close without someone holding the button, and the federally required safety reversal is out of action until it is repaired.
The repair: safety sensor repair
Garage door safety sensor repair costs $125 to $300, but a door that reverses on closing is most often solved for free by wiping the lenses and realigning the brackets — a five-minute fix that needs no tools.
Read the full safety sensor repair guide →Get a tech dispatched
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