Garage door won't close? Try this before you call anyone

Since the early 1990s every residential garage door opener sold in the US has been required to have photo-eye sensors: two small units mounted about six inches off the floor on either side of the opening, pointing at each other. One sends an invisible beam, the other receives it.

If anything interrupts that beam while the door is closing, the opener reverses. That is the feature working correctly — it is what stops a door closing on a child, a pet or a bicycle.

Holding the wall button forces the door down and bypasses the reversal, which is why that trick appears to work. It is also why it should only ever be a temporary measure.

1. Look for something in the beam

Obvious, but it is the answer more often than anything else. A bin, a bike wheel, a bag of compost, a coiled hose, a snow shovel leaning at the wrong angle. The beam sits low, so it catches things you would not think of.

2. Check the indicator lights

Both sensors have small LEDs. Typically one glows steadily to show it has power, and the other glows steadily only when it can see the opposite unit. If one is off entirely, that unit has lost power. If one is flickering or dim, they are out of alignment.

3. Clean the lenses

Dust, cobwebs and road salt film build up on the lens. Wipe both with a dry soft cloth — not a wet one, and not a solvent.

4. Realign them

Sensors are usually held in a bracket with a wing nut. Loosen it slightly and move one sensor gently until the indicator light goes solid, then tighten. They only need to be a few degrees off to break the beam. Knocking one with a car door or a leaf blower is a very common cause.

5. Look at the wiring

Follow the thin wire back from each sensor. Staples working loose, rodent damage and a wire pinched behind a stored item are all things you can spot in a minute.

If both lights are solid, the lenses are clean and the door still will not close, the problem is elsewhere. The usual candidates are the opener's travel limit settings, a worn logic board, or a track obstruction making the door bind on the way down.

That is the point to call someone. What we would ask you not to do is disconnect or bypass the sensors to make the symptom go away. It is unsafe, it is against code, and it removes the one thing standing between a closing door and whatever is underneath it.