The safety sensors — small photo-eye units mounted a few inches off the ground on each side of the track — are one of the most common reasons a garage door won't close, and one of the easiest issues to check yourself before assuming something bigger is wrong.
How the sensors work
The two sensors send an invisible beam across the bottom of the doorway. If anything breaks that beam while the door is closing, the opener reverses the door as a safety feature to prevent it from closing on a person, pet, or object. If the sensors are misaligned or blocked, the opener can behave as if something is always in the way — even when nothing is there.
Misalignment
The most common cause. Sensors can be bumped out of alignment by a stored bike, a car mirror, or even normal vibration over time. Most units have a small LED that indicates alignment status — check your opener's manual for what steady vs. blinking means for your specific model, since indicators vary by brand.
Dirt, spider webs, or glare
- Dust or spider webs on the lens can block or scatter the beam — wipe both lenses with a soft, dry cloth
- Direct sunlight hitting the receiving sensor at certain times of day can interfere with the beam
- Standing water or condensation on the lens after a storm is a common Pacific Northwest culprit
Wiring issues
If the sensors are clean and appear aligned but the door still won't close, a loose, pinched, or corroded wire connection at the sensor or at the opener unit is a common next suspect. This is usually a straightforward fix but does involve working near the opener's electrical connections, so if you're not comfortable tracing wiring, it's worth calling a technician rather than forcing it.
When sensor trouble points to something bigger
If sensor issues keep recurring after cleaning, realigning, and checking wiring, or if they're happening alongside other problems like a worn opener or an aging door, it may be worth pricing a full replacement rather than repeatedly troubleshooting an older system. Our wizard gives you an exact installed price for a new Hörmann door and opener setup in about two minutes.