9 times out of 10, a garage door that won't close is a photo-eye safety sensor problem. The sensors are the small black/silver boxes near the floor on each side of the door. They need to face each other directly with a clear line of sight. Sensor cleaning, realignment, or replacement fixes most 'won't close' issues — often free as DIY.
Step 1: Check the safety sensors
Look at the two photo-eye sensors near the floor on each side of the door. They're small black or silver boxes about 6 inches off the ground. Each should have an LED indicator (usually amber or green).
If both LEDs are solid: sensors are working — the problem is elsewhere. If one LED is blinking: that sensor is misaligned, blocked, or dirty. If both LEDs are off: sensors have failed and need replacement.
Step 2: Realign misaligned sensors
Gently rotate the misaligned sensor (the one with the blinking LED) until both LEDs go solid. The sensors need to face each other within about 1 degree of alignment. They can be bumped out of alignment by lawn equipment, kids, or someone bumping the post.
Once both LEDs are solid, try closing the door. It should now close normally.
Step 3: Clean the sensor lenses
Spider webs, dust, or pollen on the lens can break the beam. Wipe both lenses with a soft dry cloth. Don't use water or cleaning products — just dry wiping. Then check the LEDs again.
Step 4: Check for obstructions
Anything between the two sensors that breaks the invisible beam will prevent the door from closing. Common culprits: lawn equipment, sports gear, kids' toys, bicycles, or a partially-open trash can. Move anything in the path.
Step 5: If sensors are fine but door still won't close
Less common causes: (1) The 'down' limit on the opener is set too far — the door tries to close past the floor and reverses. (2) The opener force setting is too sensitive — it interprets minor resistance as an obstacle. (3) The opener itself has failed.
Limit and force adjustments are on the opener housing — refer to your opener manual or call us. Opener failure: $149 diagnostic, $149-$849 repair depending on cause.
When to call a tech
If you've checked all four sensor scenarios and the door still won't close, or if both sensor LEDs are dead (sensor failure), call us. Sensor replacement runs $89-$145; broader troubleshooting starts at $149.
Common questions.
Why does my garage door close partway then reverse?
Photo-eye sensor detecting an obstruction in the path mid-close. Could be: dirty lens (free to clean), misaligned sensor (free to realign), or actual obstruction. Check both sensor LEDs — one blinking is the sensor problem.
Why won't my garage door close all the way?
Either the 'down' limit on the opener is set wrong (door stops short before reaching the floor) or the bottom weather seal is worn and the door looks not-closed because the seal isn't compressing. Limit adjustment is on the opener; seal replacement is $95-$165.
Does the sensor light blink mean it's broken?
Not necessarily. A blinking LED on one sensor usually means it's misaligned (most common), dirty, or obstructed. Try realigning and cleaning before assuming it's broken. Solid LED on both = working; both LEDs off = both sensors dead.
How much does it cost to fix a garage door that won't close?
Most 'won't close' issues are free to fix (sensor realignment, cleaning, obstruction removal). Sensor pair replacement: $89-$145. Limit adjustment on a service call: bundled. Opener replacement (last resort): $549-$849.
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