Your garage door goes up fine but refuses to come back down. Or it starts closing, gets halfway, and reverses itself for no apparent reason. Maybe the opener light flashes a few times and nothing happens at all.
Nine times out of ten, the problem isn’t the motor, the remote, or the springs. It’s the sensors.
Garage door safety sensors are small, easy to overlook, and responsible for more “my door is broken” calls than almost any other component. The good news is that most sensor issues can be resolved in under fifteen minutes with no tools or very basic ones. This guide starts with what you’re seeing, works backward to the cause, and walks you through the fix.
What Your Door Is Doing and What It Probably Means
Before touching anything, pay attention to exactly what happens when you press the close button. The symptoms tell you where to start.
The door starts closing then immediately reverses. This is the most common sensor issue. The safety beam between the two sensors is being interrupted—either by an obstruction, dirty lenses, or misalignment. The system thinks something is in the way and reverses to protect it.
The door won’t move at all when you press close, but the opener light flashes. The sensors are telling the opener that the beam path isn’t clear. Most openers flash their ceiling light a set number of times to indicate a sensor fault. Check your opener manual for the specific flash code, but the fix is usually the same: clean and realign.
The door only closes if you hold the wall-mounted button down continuously. This is a deliberate safety bypass built into most openers. When the sensors can’t confirm a clear path, the system lets you override by holding the button—but only while you maintain physical contact. It’s not a long-term solution; it means the sensors need attention.
One sensor light is solid, the other is blinking or off. The sending sensor (usually green) emits the infrared beam. The receiving sensor (usually amber or red) detects it. A blinking receiver means the beam isn’t reaching it. A dead light on either unit points to a power or wiring issue.
For a broader walkthrough of what different garage door symptoms mean, our garage door problem identification guide covers everything from sensor faults to spring failures and track issues.
Before You Start: Safety First
Garage door sensor work is low-risk compared to springs or cables, but a couple of precautions are worth taking.
Unplug the opener from its ceiling outlet or switch off the circuit breaker before inspecting any wiring. This prevents the door from activating unexpectedly while you’re working near the tracks. Never attempt to bypass or permanently disable the safety sensors—they exist to prevent the door from closing on a person, pet, or vehicle. And if your troubleshooting leads you toward the springs, cables, or opener motor itself, stop there and call a professional. Those components operate under serious tension and electrical load.
Step 1: Clear the Beam Path
Start with the obvious. The infrared beam runs between the two sensors mounted roughly 15 centimetres above the floor on either side of the door opening. Anything breaking that beam—a broom handle leaning against the frame, a shoe, a bike tyre, a leaf caught in a cobweb—will prevent the door from closing.
Walk the full width of the opening and remove anything within the beam path. Then try closing the door again. You’d be surprised how often this is the entire fix.
Step 2: Clean the Sensor Lenses
Each sensor has a small plastic lens about the size of a ten-cent coin. Over time, dust, cobwebs, moisture film, and grime build up on the surface and weaken or block the infrared signal.
Wipe both lenses gently with a soft, dry microfibre cloth. Avoid paper towels (they can scratch) and skip chemical cleaners unless the buildup is oily—in which case a tiny amount of glass cleaner on the cloth is fine.
Cleaning the lenses solves the problem in a significant number of cases, particularly in garages that accumulate dust from nearby roads or construction, or where spiders have set up camp between the sensors.
Step 3: Realign the Sensors
This is the most common fix. Sensors are mounted on thin metal brackets that attach to the door tracks with wing nuts or small bolts. It takes very little to knock one out of alignment—a bump from a wheelie bin, vibration from the door cycling thousands of times, or even a child brushing past.
To realign them, loosen the mounting bracket on the receiving sensor (the one with the blinking or unsteady light) just enough that you can pivot it by hand. Slowly adjust the angle until the indicator light goes from blinking to solid. On some models, the light changes colour when alignment is achieved.
Once the light holds steady, tighten the bracket firmly so it stays in position. Then do a full test: open the door, close it, and place an object like a cardboard box in the beam path to confirm the safety reverse triggers correctly.
If you find the sensors keep slipping out of alignment after tightening, the bracket itself may be bent or the track mounting point may have shifted. A technician can assess whether the bracket needs replacing or the track needs adjustment—our post on garage door track repair explains how track issues affect the broader system.
Step 4: Check for Sunlight Interference
This one catches people off guard. Direct afternoon sunlight hitting the receiving sensor can overwhelm the infrared beam and trick the system into thinking the path is blocked. It’s particularly common in west-facing garages on the Sunshine Coast during late afternoon in summer.
If your door closes fine in the morning but plays up in the afternoon, sunlight is likely the culprit. A simple fix is to create a small shade tube—a short section of cardboard or PVC pipe taped around the sensor lens to block ambient light without obstructing the beam. Some aftermarket sensor shields are also available for a few dollars.
Step 5: Inspect the Wiring
If cleaning and realignment haven’t resolved the issue and one or both sensor lights remain off, the problem may be electrical.
With the opener unplugged, visually trace the thin wires that run from each sensor back to the opener unit on the ceiling. Look for wire that’s been pinched by a bracket, chewed by a rodent, pulled loose at the terminal connection, or frayed where it passes along the track. Loose terminal connections are the most common wiring fault—sometimes the wire has simply vibrated free from the screw terminal on the back of the sensor or at the opener.
If you’re comfortable with basic wiring, you can re-strip a small section of the wire end and re-secure it to the terminal. If the wire is damaged along its length or you’re not confident working with electrical connections, this is a good point to call in a professional. Faulty wiring that’s left unaddressed can cause intermittent failures that become increasingly frustrating to diagnose.
Step 6: Power-Cycle the Opener
Once the physical checks are done, a simple power cycle can clear electronic glitches in the opener’s logic board.
Unplug the opener (or switch off the breaker), wait 60 seconds, then restore power. This reboots the system and resets any fault codes the board may be holding. It won’t fix a mechanical alignment issue, but it can resolve situations where the opener has locked itself into a fault state after a power surge or brief outage.
After restoring power, test the door through a full open-close-reverse cycle to confirm everything is functioning.
What If None of This Works?
If you’ve cleaned the lenses, confirmed alignment, checked wiring, ruled out sunlight, and power-cycled the opener—and the door still won’t close properly—the issue likely sits deeper than a simple reset can reach.
Possible causes at this stage include a faulty sensor unit that needs replacing (the internal LED or photo eye has failed), a damaged opener logic board, corroded wiring connections hidden inside conduit or behind panels, or an opener lock feature that’s been accidentally activated (check your wall-mounted control panel for a lock icon or button).
Sensor replacement itself is a relatively inexpensive repair. The sensors are one of the most affordable components in the entire door system. But diagnosing whether the fault is in the sensor, the wiring, or the opener board requires testing with a multimeter and knowledge of the specific opener model. That’s where professional help saves time and guesswork. For a sense of what different repairs typically cost, our guide to garage door repair costs in Australia provides a useful benchmark.
Preventing Sensor Problems in the First Place
A few simple habits reduce the chance of sensor issues recurring.
Wipe the lenses every couple of months when you clean the garage—it takes ten seconds. Keep the area around the sensors clear of stored items that could shift and block the beam. Check the mounting brackets for tightness once or twice a year, especially if your garage gets heavy daily use. Clear cobwebs from around the sensors regularly (spiders love the warm, sheltered corner where sensors sit). And if you’re lubricating rollers and hinges as part of seasonal maintenance, take an extra minute to visually confirm both sensor lights are solid. Our guide on lubricating garage door rollers covers the full seasonal maintenance routine, and adding a sensor check takes almost no extra effort.
If your opener is reaching the end of its lifespan and sensor faults are becoming frequent, it may be worth considering a full opener upgrade. Modern units come with improved sensor technology, battery backup, and smart connectivity. Our post on automatic garage door and gate openers breaks down what’s available and what to look for.
Frequently Asked Questions
How do I know if my garage door sensors are bad rather than just misaligned? If the sensor light stays off after checking power, cleaning the lens, confirming wiring, and attempting realignment, the internal photo eye has likely failed and the sensor needs replacing. A technician can confirm with a quick voltage test.
Can I reset sensors without unplugging the opener? For cleaning and realignment, yes—the door won’t activate while it’s already in the open position. However, unplugging is strongly recommended before touching any wiring.
Why does my garage door only close when I hold the wall button? The opener is detecting a sensor fault and defaulting to manual override mode. The door will close under continuous pressure, but the underlying alignment, obstruction, or wiring issue still needs fixing.
Will sunlight really stop my garage door from closing? Yes. Direct sunlight—particularly strong afternoon sun—can overpower the infrared beam on the receiving sensor. A small shade tube or aftermarket shield solves this for a few dollars.
How much does it cost to replace garage door sensors? Sensors are one of the more affordable components to replace. The exact cost depends on the opener brand and whether wiring also needs attention, but it’s typically at the lower end of the repair spectrum.
Still Can’t Get Your Sensors Working? We Can Help.
If you’ve worked through every step in this guide and your door is still refusing to cooperate, the team at Sunshine Coast Garage Door Guys can diagnose and fix the issue—usually in a single visit.
Our qualified technicians troubleshoot and repair all opener brands and sensor systems across every Sunshine Coast suburb from Caloundra to Noosa. We carry common replacement sensors on our service vehicles so most faults can be resolved on the spot without a second appointment.
Here’s what we offer:
- Full sensor diagnosis – We test alignment, wiring continuity, and sensor output to pinpoint the exact fault rather than guessing.
- Same-day sensor replacement – If a sensor has failed, we replace it, realign the pair, and test the full safety cycle before we leave.
- Opener inspection and servicing – If the fault sits in the logic board or motor rather than the sensors, we diagnose that too and provide an upfront quote.
- Emergency call-outs – If a sensor failure has left your door stuck open and your property unsecured, we offer same-day emergency service to get you sorted.
Call us on (07) 5451 8776 or request a free quote online today. You can also email us at [email protected] or visit us at Unit 104/25 Chancellor Village Blvd, Sippy Downs QLD 4556.
