

Openers · Maryhill
Photo-Eye Sensor Alignment or Replacement in Maryhill
After a cold night the door stays open until the garage warms up.
In plain words
Your opener has been trying to tell you what is wrong. The head unit flashes its light a set number of times, or blinks a pattern on its up and down arrows, and each pattern maps to a cause on the maker's chart: beam blocked or misaligned, wire cut or disconnected, wires reversed or shorted. Down at the floor, many sensor pairs carry an indicator on each side, though some older pairs light only the receiver; check that model's chart, since a receiving light going out or flickering usually points to alignment. The technician reads both sets of signals first, which is why the repair usually takes one visit.
How the visit goesThe small light on one of the sensors near the floor has gone dark, or it flickers when someone walks past the track. The other one glows steadily. The door refuses to close from the car.
Photo-Eye Sensor Alignment or Replacement
How the visit goes


Starting with the story
The first minutes are spent listening. What does the door do when close is pressed: drop and bounce, stay put, or close only while the wall button is held? Does the opener light blink, and how many times? When did it start, and what changed around then: a car bumped the track, a storm, shelving went up, the garage was reorganised, the first frost arrived? Does it happen at all hours or only on bright mornings? Those answers usually point at one of a handful of causes before a single tool comes out, and they decide whether the technician heads for the brackets, the wire or the head unit first.
Straightening or replacing the brackets
A bent bracket is straightened where the metal allows and replaced where it has cracked or rusted through. New brackets are chosen to suit the mounting: a track-mounted clip that rides the vertical rail, or a right-angle bracket anchored to the wall or the concrete where the track sits too far back. Fasteners that vibrated loose are replaced with the right carriage bolts and wing nuts rather than reused. Where a bracket has been sitting in salt slush every winter, it is set a touch higher within the permitted range and the mounting is sealed against the wall so water stops running behind it.
The monthly beam test
The habit worth keeping takes about a minute. Once a month, with the door open, press close on the wall control and, as it moves down, pass a broom handle through the beam near the floor. The door should stop and climb back to fully open. Then lay a 2x4 flat under the middle of the door and close onto it; the door should touch it and reverse. If either test fails, stop using the opener; close the door first if it is not already closed, then use the manual release, and get help moving it by hand if it feels heavy or will not hold. A door that passes both tests is doing its job.
Photo-Eye Sensor Alignment or Replacement
In the van
Multimeter
Insulated wire staples
Wall or floor angle brackets
Receiving-eye sun shade
Wire connectors

Photo-Eye Sensor Alignment or Replacement
What affects the quote
Wall or floor mounting with anchors
Mounting into concrete or masonry rather than onto the track means drilling, anchors and sealing against water, which takes more time than clipping to the rail.
Type of kit
Some replacement kits contain only the two sensors with connectors, while others include brackets and a full length of wire. The kit that suits the opener and the state of the existing hardware is what is quoted.
Access to the doorway and the head unit
A clear strip along the floor and a reachable head unit make for a direct job. Shelving, vehicles or stored goods that must be moved to reach the sensors, wire or terminals add time.
What to have ready
- When did it begin, and what was different that week: a bump, new shelving, a storm, a frost?
- Is there frost, snow, slush or salt around the sensors in winter?
- What do the two small sensor lights show: both steady, one dark or flickering, or both dark?
Photo-Eye Sensor Alignment or Replacement: questions
QuestionsCould the wiring be the problem rather than the sensors?
Frequently. The sensors are fed by a thin two-conductor wire from the head unit that crosses the ceiling and drops down both sides of the door, and it is pierced by staples, cut by shelving screws, chewed by mice or pulled from its terminals more often than a sensor fails. Both sensor lights dark, or an opener code for an open or reversed circuit, points to the wire. The technician tests the run with a meter and repairs or replaces the damaged section.
How high off the floor should the sensors sit?
Low. The industry checklist expects the beam no more than roughly 15 cm (6 in) up from the floor, so that a small child, a pet or a bicycle wheel breaks it. Both sensors are set at the same measured height and level with each other, since a difference of a couple of centimetres is enough to lose the beam. Within that rule the technician can raise them a little to keep them out of the strip where slush collects.
Will my phone app or hub still work after the sensors are changed?
Yes. The sensors are wired to the head unit, and the app or hub simply talks to that unit, so nothing about the connection changes. What you will notice is the fault code clearing: apps that reported the sensors as obstructed or not aligned show the door as ready to close again. If an app or hub still holds an old code after the work, refreshing it or cycling the door from the app once clears it.
Related services

- Chain-Drive Opener RepairThe door opens about a third of the way and stops.
- Belt-Drive Opener RepairIt is minus twenty in the detached garage and the door climbs in jerks, the belt stiff as a board.
- Garage Door Opener ReplacementThe bedroom above the garage shakes every morning at six when the chain drive fires up.