Door won't close? Nine times out of ten, it's the sensors.
Last updated April 23, 2026
Federal law (UL 325) has required photo-eye safety sensors on every residential opener since 1993 — two small boxes 6 inches off the floor on either side of the door. Green LED on the sender, red or amber LED on the receiver. If either light blinks or goes out, the opener refuses to close. Most 'dead' garage doors are actually a 30-second sensor fix.
What's included in this service?
- Sensor alignment with laser and manufacturer spec (bubble level on bracket)
- Sensor wire inspection end-to-end (staples, rodent damage, age)
- Sensor bracket straightening when bumped or hit
- Sunlight-blind sensor diagnosis (infrared washout)
- Sensor replacement (matched-pair for the opener brand)
- Wiring reroute for water-damaged or corroded runs
- Wall-button low-voltage testing
- Safety-reverse mechanical test after alignment
When do you need this service?
- Opener runs, door starts down, then reverses back up
- LED on one sensor is dark, flickering, or wrong color
- Door closes fine in the morning but not in afternoon sun
- Something hit the bracket and it's now pointing slightly off
- Opener beeps and flashes 10 times when you press the button
- Cobwebs, dust, or dead insects blocking the lens
What do homeowners ask about Sensors?
What's the LED supposed to do?
Sending sensor (usually one side only): solid green. Receiving sensor: solid red, amber, or green depending on brand — LiftMaster is green, Chamberlain varies, Genie is red. If either side blinks, flickers, or goes out, the beam is broken. Sun hitting the receiver lens at the wrong angle can also cause a blink that magically clears at sundown.
My sensor lens is dusty — do I just wipe it?
Yes, that's the first thing to try. A soft dry cloth on both lenses fixes about 15% of sensor issues. Next, eyeball the alignment — both sensors should point straight at each other with no tilt. If that doesn't do it, the wiring or the sensor itself is the issue.
Why does the door close fine in the morning but not afternoon?
Sun hitting the receiver lens. If the garage faces west or south, late-afternoon sun can wash out the infrared beam the same way a flashlight into your eye blinds you. Fix is to reposition the sensor a few inches back, shield the lens with a strip of black tape along the top, or swap to sun-hood sensors that come with a built-in visor.
Can I bypass the sensors?
Not legally on a residential opener — UL 325 requires them and an opener wired around the sensors isn't compliant. It's also a real hazard: the sensors are what keep the door from closing on a kid, pet, or bike left in the threshold. If the sensors are broken, we fix them. We don't wire around them.
Where do we offer Sensors in San Diego County?
We provide sensors in every city and community in San Diego County. Pick your city for local climate notes and service specifics.
See sensors in all 47 cities
Homeowners who hired us for this
Called at 7:30 a.m. when I heard the bang — broken torsion spring, car trapped inside. A tech was in the driveway by 9:15 with a matched pair ready to install. Flat-rate quote before he started, done in under an hour. Felt like the old days of someone actually showing up.
Got three quotes for a new door after ours gave out. Lift Pro was the only one that talked about the HOA committee requirements up front and offered a wood-grain steel that got approved on the first try. Installed in one day, clean work, hauled the old one off.
Old chain-drive opener was louder than my teenagers. They pulled it, installed a quiet belt-drive LiftMaster with Wi-Fi, and walked me through the app before leaving. It closes itself now when I drive away. Crew was on time and actually picked up their packaging.
Need sensors in San Diego County?
Call for a free quote. Most work scheduled within the week.