Sound familiar?Burlington
- The call
- You press the remote, the door drops a few centimetres, then climbs straight back to the top while the opener light blinks. Nothing is under the door. It has done this every evening this week.

There are no sensors at the floor at all, or a previous owner has wired the pair together up beside the motor so the beam never crosses the doorway. A home inspector has just pointed it out.
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.
Sound familiar?Burlington
Photo-Eye Sensor Alignment or Replacement · Burlington

Scene 1
The two sensors have to sit at the same height, level, and facing each other squarely, no higher than about 15 cm (6 in) above the floor so the beam catches a small child or a pet. The technician measures both sides, because a bracket that has slipped a couple of centimetres down a track leg is enough to lose the beam. Each bracket is checked for bends from a bumper or a bin, for loose carriage bolts or wing nuts, and for rust where salt slush has sat against it for winters on end. A bracket screwed to a wall or the floor is checked for anchors that have worked loose.
Scene 2
Alignment is done with the door open and the lights in view. The technician sets both sensors to the same measured height, loosens the wing nut on the receiving side, and turns the sensor a fraction at a time until its indicator changes from dark or flickering to steady. The nut is tightened while the light is watched, because a sensor can drift as the fastener bites, and the sending side is treated the same way. Brackets are checked for play and the wire is re-clipped so it cannot tug the sensor out of line. A steady light on both sides, held through a few door cycles, is the standard.
Scene 3
Should the door start bouncing back up in the future, you know the order to check. Look along the floor for anything in the beam. Look at the two sensor lights for a dark or flickering one. Look at whether the door backs up as soon as it starts or only after touching something, since the second points to the door's settings rather than the beam. Note whether the opener light is flashing and how many times. With those four facts the cause is usually obvious, and if a visit is needed, the technician arrives already knowing where to begin.
What shapes the quoteDynes Garage Door Experts
FeesSame any hour
Use the door in a way that keeps you in control. If the opener closes only while the wall button is held, do that only while you can see the whole doorway and nobody is near it. Otherwise close the door first if you can, then move it by hand with the manual release, and get help if it feels heavy or binds. Keep children and pets clear during any test. A door that reverses is being cautious on your behalf.
Not any, no. Sensors are matched to the opener's make and generation, and a board from one era may ignore sensors from another even when the wires fit. The technician reads the model from the head unit label and fits the pair listed for it. Some operators accept a documented universal pair, and those are used where the maker lists them as suitable; on a very old unit with no compatible pair, a modern operator is the way forward.
Gently, with a soft dry or lightly damp cloth, the way you would clean eyeglasses. Never scrape a lens or use a solvent, since a scratched or clouded lens scatters the beam. Wipe both sensors, then check that the receiving light comes on steadily. If a lens frosts on cold mornings, give it a few minutes to clear or dry it with a cloth. A quarterly wipe keeps dust, cobwebs and salt film from building up.
HaltonOntario
Photo-Eye Sensor Alignment or Replacement · Dynes, Elizabeth Gardens, Longmoor, Orchard, Port Nelson, Roseland, Strathcona Gardens
Every square is one home in a hundred.
On-site assessment
There are no sensors at the floor at all, or a previous owner has wired the pair together up beside the motor so the beam never crosses the doorway.
(289) 816-2884, open 24/7.
On-site assessment preferred · (289) 816-2884, open 24/7