Photo-eye sensors sit six inches off the floor and stop the door from closing on anything in its path — when they're dirty, misaligned, or wired badly, the door reverses for no visible reason or refuses to close at all. Alfonso diagnoses and fixes sensors across San Francisco same-day: realignment runs $90–$140, and a new sensor pair installed runs $140–$260.
| Sensor cleaning, realignment, and function test | $90–$140 |
| New sensor pair, wired and aligned | $140–$260 |
| Wiring repair (chewed, pinched, or corroded runs) | $110–$220 |
Typical San Francisco and Bay Area ranges (parts + labor), last updated July 2026 — see the full SF garage door cost guide. You get an exact, upfront quote before any work begins — call (415) 494-4774 or book online.
Unlike dangerous spring or cable repairs, troubleshooting safety sensors is often safe for a homeowner to attempt. Many sensor issues are simple fixes.
If the sensor lights will not come on at all, even after alignment.
If you’ve cleaned and aligned them, but the door still won’t close.
If the sensors are physically damaged (e.g., crushed, or hit by a car).
If you see damaged, cut, or frayed wiring.
If you suspect the problem is with the opener’s main logic board.
Our technicians at Alfonso Garage Door can quickly diagnose if it’s a simple alignment, a bad sensor that needs replacing, or a more complex wiring or logic board issue.
Wipe the sensor lenses with a clean cloth.
Visually inspect the area around them and clear any new clutter or cobwebs.
Gently check that the sensor brackets are not loose or bent.
Test the sensors by closing the door and passing an object (like a paper towel roll) through the beam. The door should immediately reverse.
Schedule a professional tune-up. A technician will test the sensor force and alignment, check the wiring, and make sure the entire system is working safely.
Misalignment: Being bumped by garbage cans, bikes, or kids.
Dirt & Debris: Dust, cobwebs, or yard debris blocking the lens.
Direct Sunlight: Strong, direct sunlight shining into the "receiver" eye can blind it.
Damaged Wires: Wires can be cut by weed whackers, chewed by rodents, or corroded by moisture.
Age/Water Damage: The sensors are electronics and can fail over time, especially if they get wet.
Owner
Leads the team on garage door installations and repairs.
Technician
Skilled in maintenance, repair, and troubleshooting of all residential and commercial garage doors.
Technician
Experienced in spring replacement, opener installation, and emergency garage door services.
Technician
Specializes in cable, roller, and track repairs.
We follow all DASMA Garage Door Safety Guidelines on every job.
Our safety protocols and training are aligned with OSHA Safety Standards to protect both our technicians and your property.
Call and tell us what the door is doing. You’ll get an exact quote before any work begins.
Our certified technicians arrive on time with fully stocked service vehicles, ready to complete most repairs on the first visit.
All our work is backed by warranties on parts and labor.
We provide follow-up service and are always available for questions or additional needs.
A slow, steady blink usually means the two eyes are slightly out of line, not dead. The door still closes because the beam is barely connecting. Get the brackets adjusted soon, because a sensor in that state tends to fail all the way on a cold, damp morning, right when you need to leave.
Yes, and in the Outer Sunset it happens all the time. The marine layer leaves a thin salt film on the lens overnight, and a single web strand across it scatters the beam enough to trigger blinking and reversal. Wipe both lenses with a dry, soft cloth, no cleaners, and check nothing is sitting in the beam path.
Look at the lights. If both eyes glow solid and steady and the door still reverses, the board or the wiring is usually at fault, not the eyes. A blinking light with clean, aligned sensors points the same way. We test the whole opener on every sensor call, because a failing board can copy sensor symptoms almost perfectly.
Watch the small LEDs on each sensor: on most brands, a steady light on both means they see each other, while a dark or flickering LED means the beam is broken or the sensor has lost power. Also try holding the wall button down — most openers will force-close past a sensor fault that way. If it closes while held, you've confirmed the sensors.
If the fix is cleaning and realignment, expect $90–$140 in San Francisco. A failed sensor pair replaced and wired runs $140–$260, and repairing damaged wiring runs $110–$220. We tell you which situation you have — and the exact price — before doing anything.
That's low sun. West-facing garages — common along the avenues — catch direct sunlight into one photo-eye late in the day, which floods the receiver and mimics a blocked beam. Sun shields or swapping which side holds the receiver usually solves it. Fog-belt homes get the opposite problem: condensation filming over the lens on damp mornings.
We won't do that, and we'd ask you not to either. The photo-eyes are the system that keeps a closing door off a pet, a kid chasing a ball, or your bumper. Bypassing them also violates the federal safety standard openers are built to. The honest fix is nearly always under $260 — not worth the risk of skipping.
Yes — rodent-damaged and pinch-damaged sensor wiring is a routine repair for us, especially in garages with stored boxes stacked against the walls. We re-run the low-voltage wire, secure it out of reach, and test the full safety circuit. If the copper has corroded inside the insulation, common in damp garages near the beach, we replace the run rather than splice it.
Often handled in the same visit as safety sensor repair:
Same-day, true 24/7 safety sensor repair across San Francisco, the Peninsula, Marin, and the East Bay, including:
Our shop is at 1726 Great Hwy in the Outer Sunset. These are the SF neighborhoods where we run safety sensor repair calls most often:
SMS consent will not be shared with any third party and an affiliate for marketing, nor will any phone numbers for SMS purpose
