Garage door safety sensors are the small units mounted a few inches off the floor on either side of the track. They send an infrared beam between them, and if that beam is broken while the door is closing, the door reverses - a safety feature required on all openers manufactured since 1993.
Common sensor problems
Blinking light on one sensor. Almost always misalignment - the two sensors need to point directly at each other. A solid light on both usually means they’re aligned correctly.
Door won’t close at all. If the sensors are blocked, dirty, or misaligned, most openers refuse to close as a safety default.
Door closes but reverses partway. Sunlight hitting a sensor directly can sometimes interfere with the infrared beam - this is more common with west- or east-facing garages at certain times of day.
Simple fixes to try first
- Wipe both sensor lenses clean of dust or cobwebs
- Check that nothing (a stored item, a stray cable) is blocking the beam
- Gently adjust each sensor’s angle until both lights are solid rather than blinking
- Confirm both sensors are securely mounted and haven’t been bumped out of position
If the lights stay misaligned even after adjustment, a bracket may be bent or a sensor may have failed electrically - at that point it’s worth having a technician inspect and, if needed, replace the unit.