If your garage door reverses immediately after you close it, closes only while you hold the wall button, or has an opener light that blinks several times when you try to close it — almost certainly you have a sensor problem. Safety photo-eye sensors are required on all modern garage door openers, and when they malfunction, the opener is programmed to refuse to close the door. Here is what you need to know.
How Safety Sensors Work
Every modern garage door opener has two photo-eye sensors mounted near the bottom of the door tracks, one on each side. One sensor emits an infrared beam and the other receives it. When the beam is unbroken, the opener knows the door path is clear and will close normally. When the beam is interrupted — by a person, pet, object, or sensor misalignment — the opener reverses or refuses to close.
Why Your Sensors Might Be Failing
The most common cause is misalignment — the transmitter and receiver are not perfectly aimed at each other. This can happen from a minor bump during parking, from hardware loosening over time, or from thermal expansion in Calgary’s temperature extremes causing the mounting bracket to shift. The second most common cause is a dirty or frosted lens — the small plastic lenses on each sensor unit can accumulate dust, spiderwebs or frost in Calgary winters, blocking the infrared beam. The third cause is actual sensor failure — the LED or receiver component has burned out.
What Each Sensor LED Colour Means
The sending sensor (transmitter) should have a solid amber or yellow LED at all times. The receiving sensor should have a solid green LED when aligned. If the green LED is blinking, the receiver is not receiving the beam properly — alignment is off or the lens is dirty. If either LED is completely off, there is a wiring or component failure. Try gently cleaning both lenses with a dry cloth and slowly adjusting the angle of the receiver sensor until the green LED becomes solid.
Frequently Asked Questions
Why does my garage door reverse immediately after closing?
The safety sensors are misaligned, blocked or dirty. Check that both sensor LEDs are solid (not blinking) and clean the lenses with a dry cloth. If the green receiving sensor LED is blinking, gently realign it until it becomes solid.
Why does my garage door only close when I hold the wall button?
Holding the wall button bypasses the safety sensors. This means the sensors are malfunctioning. The door can close while bypassing them, but this is not a long-term solution — call Super G&R Garage Door Repairs for proper sensor repair.
Why does my garage door reverse in the afternoon but not in the morning?
This is sun interference — low-angle afternoon sun hits the receiving sensor directly and overwhelms it. It's common in Calgary in September and October. We install sensor shields that solve this immediately.
How much does garage door sensor repair cost in Calgary?
Sensor diagnosis and realignment costs $120–$180 + GST. If sensors need replacement, parts and labour are within the same range. Same-day service across Calgary.
Ready to book? Call (825) 438-2406 or visit our contact page. Same-day service across Calgary, Airdrie, Okotoks and surrounding communities.
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