Garage Door Sensor Safety: Auto-Reverse and the 1993 Law

Will my garage door reverse if a child or pet is under it?

A properly working garage door will reverse off a child or pet, because federal law has required auto-reverse on every opener since 1993. But sensors drift, lenses get dirty, and force settings slip, so a door that worked last year may not reverse today. Test it to be sure.

There are two independent safety systems working together. The contact-reversal mechanism senses resistance when the door bottom strikes an object and backs the door off. The photo-eye safety sensors, mounted about six inches above the floor on each track, shine an infrared beam across the opening and reverse the door the instant that beam is broken. A child crawling under the door should never reach the threshold, the beam catches them first.

The problem is that neither system is permanent. Springs weaken and shift the door’s balance, which changes how the opener reads resistance. Sensor brackets get bumped by a bike or a snow shovel. Lenses fog with condensation through an Ottawa winter. Any of these can leave a door that closes on something it should reverse off. That is why the two-minute tests below matter more than the year your opener was made.

How do I test my garage door auto-reverse? (2 tests)

Run two separate tests every month. First the contact-reversal test with a 2x4 board, then the photo-eye beam test. Each takes under a minute. The door must reverse fully on both. If it fails either one, stop using it and book a repair, because the door is genuinely unsafe.

These are the same checks a technician runs at the end of a full garage door tune-up and safety inspection. Do them yourself between visits. Both follow the step list at the top of this page.

The contact-reversal test (the 2x4 board test)

Lay a flat 2x4 piece of lumber on the floor directly under the centre of the open door, on the threshold where the door bottom lands. Press the wall button to close. When the door bottom meets the wood, it must stop and reverse to fully open within about two seconds.

If the door keeps pushing down on the board, crushes it, stops dead without reversing, or only pauses and then continues, the contact-reversal is set wrong or worn out. The down-force and travel-limit settings on the opener motor head control this, and they need careful adjustment. A flat board is safer and more consistent than a roll of paper towel, which can compress unevenly and give a false pass.

The photo-eye sensor test (wave an object through the beam)

Press the wall button to close the door, then pass a broom handle, a box, or your foot through the opening about six inches above the floor, into the path of the infrared beam. The door must reverse and return to fully open the moment the beam breaks.

Keep your hands out of the door’s actual path, only break the beam, not the door’s travel. If the door keeps closing after you cross the beam, the sensors are not protecting anyone. That is the more common failure, and it is usually a fast fix: cleaning, realignment, or a loose wire, rather than a new opener.

What is the 1993 garage door safety law?

In 1993, U.S. federal law made photoelectric sensors or an equivalent non-contact device mandatory on every new residential garage door opener sold. The law followed a Consumer Product Safety Commission push after dozens of children were trapped or killed by closing doors. It works alongside the UL 325 standard that manufacturers must meet.

Before the law, many openers had only basic contact reversal, which still required the heavy door to physically strike a small child before it would back off. A two or three year old does not always trigger enough resistance to reverse a 200 to 300 pound door reliably. The photo-eye beam solved that by stopping the door before contact ever happens. Although the mandate is U.S. federal law, every major brand sold in Ottawa, including LiftMaster, Chamberlain, and Genie, builds to the same standard, so Canadian homes get the same protection.

What UL 325 and the CPSC require on every opener

UL 325 is the safety standard that defines how garage door openers must detect and respond to obstructions. The Consumer Product Safety Commission backs it through federal regulation. Together they require two layers of entrapment protection on every opener, so that if one fails, the other still stops the door.

The first layer is inherent reversal, the contact mechanism that reverses the door when it meets resistance. The second is a secondary entrapment device, which for almost every modern opener means the pair of photo-eye sensors near the floor. A myQ smart opener from LiftMaster or Chamberlain adds remote alerts and the ability to close the door from your phone, but the same two physical safety systems still have to pass. No app feature replaces a working beam.

Why won’t my garage door close, and the light is blinking?

A blinking opener light almost always means the photo-eye sensors are blocked, dirty, or misaligned, so the opener refuses to close and flashes to warn you. It is a safety feature, not a breakdown. Clean both lenses and realign the brackets until the LEDs glow steady, and the door will close again.

On most LiftMaster and Chamberlain units the overhead light flashes a set number of times to signal a sensor fault. The door will still open, but it will not close from the button, or it reverses immediately after starting down. This is the single most common reason a garage door won’t close. Work through the sensor checks before assuming the opener is broken.

Misaligned or dirty photo-eye sensors

The two sensors must point straight at each other at exactly the same height for the beam to connect. A bump from a car door, a bike, or a snow shovel knocks a bracket out of aim and breaks the beam. Dust, cobwebs, road salt, and spider webs on a lens do the same thing.

Wipe both lenses with a soft, dry cloth, then look at the LEDs. One sensor sends and should glow steady, the other receives and should also glow steady, often green on the sending side and red or amber on the receiving side depending on the brand. A receiving LED that is dark or flickering means the beam is not landing. Loosen the wing nut, tilt the sensor until the LED locks on steady, and tighten. For wiring faults or sensors that will not hold alignment, book garage door sensor and opener repair in Ottawa.

Loose wiring, sun glare and cold-weather faults

Not every sensor fault is dirt or aim. The thin sensor wires are easily nicked by a staple, a ladder, or rodents, which interrupts the beam. Direct low sun shining into the receiving lens can also wash out the beam and trip a false block, common in the early morning or late afternoon.

Cold weather adds its own problems. Ottawa and Gatineau temperature swings put condensation and frost on the lenses, and cold can shrink loose brackets out of alignment overnight, which is why a door that closed fine in fall suddenly refuses in January. Wipe the lenses dry, shade a sun-glared sensor, and check the wire runs for breaks. If the door still will not close, a technician can trace the circuit and replace a damaged sensor, usually starting from $150 for opener and sensor repair.

Is it safe to bypass or disable the safety sensors?

No. Bypassing the sensors, by holding the wall button to force the door shut or unhooking the beam, removes the only protection that stops the door on a child, pet, or car. It is unsafe and defeats the entire purpose of the 1993 law. Fix the fault instead.

We hear it often: the door will not close, so someone holds the button down to override it, then leaves it that way. The trouble is that the override only works while you hold the button, and it trains the door to ignore the one system designed to catch a person underneath. Most sensor faults are a quick alignment or cleaning, not a new opener, and we will tell you straight which it is. A working beam costs nothing to keep and could save a life. Walk through every layer in the garage door safety and DIY-vs-pro guide before you ever consider an override.

How do I keep kids and pets safe around the garage door?

Test the auto-reverse and the beam every month, keep children and pets clear while the door moves, mount the wall control out of a child’s reach, and never let kids play with remotes. Watch the door complete a full cycle rather than walking away mid-close. These habits prevent almost every garage door injury.

Teach children that the garage door is not a toy and that they should never run under a moving door or try to beat it. Keep the wall-mounted button at least five feet up so a small child cannot reach it, and store remotes where kids cannot grab them. Pets are easy to miss, a cat or small dog can dart under a closing door in a second, so confirm the opening is clear before you press the button. For a printable monthly routine, use the homeowner garage door safety inspection checklist and run it alongside a full garage door tune-up and safety inspection once a year.

Sensors failing a test? Book sensor and opener repair

If your door fails the 2x4 board test or the beam test, it is unsafe and should not be used until it is fixed. Call (613) 255-1968 today. Most sensor faults are a fast alignment, cleaning, or wiring repair, not a new opener, and we service every brand.

HUSH is owned by Omar, a factory-trained technician, and we fix LiftMaster, Chamberlain, Genie, and every other major opener. Sensor and opener repair starts from $150, and the service call is free with any repair over $250, with no overtime fees. Every job is covered by our 90-day Done-Right Promise. We come to you across the city, including same-day service in Orleans and the east end and the rest of Ottawa and Gatineau. If the beam is fine but the door still reverses or refuses to close, it may be a force-setting or track issue, so see why a garage door won’t close or call and we will diagnose it on the spot.