Garage Door Sensor Alignment Across Australia
Door Reversing? Sensor Fault? Fixed Same Day.
Quick summary
If your garage door won't close, reverses immediately, or the opener light is flashing, a sensor fault is the most likely cause. Most fixes take 30–45 minutes and cost $80–$160. In QLD and WA, spider webs in the sensor housing are surprisingly common — a $90 clean and realignment clears it. Same-day service available.
Last updated: May 2026 · By the Able Garage Doors team
How garage door sensors work
Every Australian-market garage door opener — B&D, Merlin, ATA, Centurion — is required to have a pair of safety sensors fitted near the bottom of the door tracks. One sensor transmits an infrared beam; the other receives it. While the door is closing, that beam must be unbroken. If anything interrupts it — an object, a misaligned bracket, or even a cobweb — the opener immediately reverses the door.
It's a mandatory safety feature, not a fault you can bypass. The good news is that most sensor issues are straightforward: a quick clean, a bracket adjustment, or a sensor replacement if the unit is damaged.
Signs of a sensor problem
- Door won't close at all — immediately reverses after touching the ground or before it gets there
- Indicator light on one of the sensors is blinking or off
- Opener light flashes a specific number of times (indicates a sensor fault code)
- Door only closes when you hold the wall button (manual override)
- Door closes fine at night but not during the day (sunlight interference)
In Queensland and WA, spiders are a genuine and regular cause of sensor failure. The warm plastic housing is an attractive nesting spot, and a single strand of web across the sensor lens blocks the beam entirely. We see several of these per month in Brisbane and Perth.
What we do
- Diagnose the specific sensor fault — alignment, obstruction, wiring, or sunlight interference
- Clean the sensor lenses and check for cobwebs or debris in the housing
- Realign the brackets until both indicator lights are solid
- Inspect the sensor wiring for damage, fraying, or loose connections
- Replace sensors if physically damaged or faulty
- Test the auto-reverse function with a physical obstruction (roll of paper across the beam) to confirm it's working to Australian standards
What it costs
Sensor clean and realignment: $80–$120. Wiring repair: $100–$160. Sensor replacement (pair): $120–$200 including parts and labour. Sunlight shield fitting (bracket-mounted): add $40–$60 — worth it for east or west-facing doors that catch direct sun in the afternoon.
A recent job
Liz in Chermside had been holding the wall button down to close her door for about two weeks — the remote wouldn't close it, but the wall button worked fine. That's a classic sign the sensors are reporting a fault: the wall button bypasses the sensor check on many Merlin models. When we checked, there was a small huntsman web across the left sensor lens — invisible unless you looked closely. Cleaned both sensors, confirmed alignment, tested the auto-reverse. $90 and 25 minutes. She'd been holding that button twice a day for two weeks.
Frequently asked questions
Why does my garage door keep reversing before it closes?
The most common reason is a blocked or misaligned safety sensor. The two sensors (one transmitter, one receiver) sit near the bottom of the tracks and shoot an infrared beam across the door opening. If anything breaks that beam — a cobweb, a dust build-up, a shifted bracket, or even bright afternoon sunlight at certain angles — the opener reverses the door as a safety measure.
What are the safety sensors on a garage door?
They're photoelectric sensors — an infrared beam transmitter on one side and a receiver on the other. If something breaks the beam while the door is closing, the opener reverses immediately. They're a mandatory safety feature on all AU-market openers, and if they're not working properly, the opener won't close the door at all.
How do I know if my sensors are aligned?
Most openers have an indicator light on the sensor housing. If both lights are solid (not blinking), the beam is intact and the sensors are aligned. A blinking or off light on the receiver side usually means the beam is broken or misaligned. On B&D and Merlin units, the opener light will also flash a specific number of times to indicate a sensor fault.
Can I realign the sensors myself?
Sometimes. If the sensor bracket is just slightly nudged, you can loosen the wing nut, move the sensor until both indicator lights go solid, and re-tighten. But if the issue is a cobweb, a wiring fault, a damaged sensor, or sunlight interference, DIY realignment won't fix it. If you've tried the obvious adjustments and the light's still blinking, call us.
What causes sensors to go out of alignment?
The most common causes are: something bumping the bracket (a broom, a bin, a car mirror), vibration from the door operation loosening the mounting over time, spider webs in QLD and WA (extremely common — spiders love the warm housing), and direct sunlight hitting the receiver at certain times of day, which overwhelms the infrared signal.