You press the button. The garage door starts to lower — then stops and reverses. Or it won’t close at all, and the opener light flashes repeatedly. For homeowners in Sammamish, WA and across the Eastside, this is one of the most common garage door problems we get called about. In nearly every case, the culprit is the safety sensors.

What Are Garage Door Safety Sensors?

Safety sensors (also called photo-eye sensors) are the two small devices mounted near the bottom of your garage door tracks — one on each side. They project an invisible infrared beam across the opening. If anything breaks that beam while the door is closing, the opener automatically reverses to prevent injury or damage.

This is a federally required safety feature on all garage door openers manufactured after 1993. They protect children, pets, and anything else that might be in the path of a closing door.

How to Read the Indicator Lights

The fastest way to diagnose a sensor problem is to look at the LED indicator lights on each sensor unit:

• Both lights solid (green sending, amber/red receiving) — sensors are aligned and working correctly
• Receiving sensor blinking or off — sensors are misaligned, dirty, or blocked
• No lights at all — wiring issue or sensor has lost power
• Opener light blinks 10 times (LiftMaster/Chamberlain) — classic sensor misalignment signal
• Opener light blinks 4 times — sensor obstruction or wiring problem

5 Reasons Your Garage Door Sensor Isn’t Working

1. Misalignment

The most common cause. Sensors can be nudged out of position by a bumped garbage can, a child’s bike, or even vibration over time. The two sensors must face each other directly at the same height for the beam to connect.

Fix: Loosen the wing nut or bracket screw on the receiving sensor (the one with the blinking light). Gently pivot it until the light goes solid, then retighten. Don’t overtighten — this will knock it out of alignment again.

2. Dirty Lenses

In the Pacific Northwest, garage floors collect moisture, dust, and debris year-round. A thin film of grime on the sensor lens is enough to interrupt the beam.

Fix: Wipe both sensor lenses with a clean, dry cloth. Avoid chemical cleaners — a dry microfiber wipe is all you need.

3. Direct Sunlight Interference

In the late afternoon, direct sunlight shining into the garage can overpower the sensor beam — especially in west-facing garages in Sammamish, Issaquah, and Bellevue during summer months.

Fix: This is often a temporary issue that resolves as the sun moves. If it’s a persistent problem, a small piece of cardboard taped as a sun shield around the receiving sensor can eliminate the interference without blocking the beam path.

4. Wiring Damage

The thin wires connecting the sensors to the opener motor unit run along the garage wall and track. They can be pinched, cut, or chewed by rodents — particularly in older garages or homes where the wiring hasn’t been inspected in years.

Fix: Inspect the full wire run visually. Look for fraying, pinch points at the track brackets, or breaks near the motor unit. Damaged wiring requires professional repair — splicing sensor wires incorrectly can cause intermittent failures that are difficult to diagnose later.

5. Failed Sensor

Sensors typically last 10+ years, but they do fail — especially after power surges or if water has entered the housing. If the indicator light is completely off despite confirmed power and intact wiring, the sensor unit itself may need replacement.

Fix: Sensor replacement is a 30-minute professional job. Same Day Garage Door Service carries LiftMaster-compatible sensors for most major opener brands and can typically replace them same day in Redmond, Sammamish, and the rest of the Eastside.

What You Can Fix Yourself vs. When to Call a Pro

Most sensor issues fall into two categories:

Safe to DIY: cleaning the lenses, realigning a sensor that’s been knocked slightly out of position, removing a physical obstruction from the sensor path.

Call a professional: any wiring repair, sensor replacement, persistent misalignment that returns after adjustment (usually indicates a bent bracket or damaged track), and any situation where the door reverses unexpectedly even with sensors appearing aligned.

Attempting to bypass or disconnect sensors is never the right solution — doing so removes a critical safety feature and can void your opener warranty.

Frequently Asked Questions

Why does my garage door close with the wall button but not the remote?

Most openers allow the wall button to override a sensor fault in “hold-down” mode — you hold the button until the door fully closes. This confirms the problem is sensor-related, not the opener itself. It’s a temporary workaround, not a fix.

Can I test my sensors without closing the door?

Yes. With the door open, pass your hand or a broom handle through the beam path near the sensors. The opener light should flash, indicating the beam was interrupted. If it doesn’t respond, the sensors aren’t communicating with the opener.

How often should garage door sensors be checked?

Test your sensors monthly as part of basic garage door maintenance — it takes 10 seconds. Simply start the door closing and pass an object through the sensor beam. The door should reverse immediately. If it doesn’t, call a technician.

My sensors look aligned but the door still won’t close — what else could it be?

If sensors appear aligned and clean but the door still reverses, check for: an object partially in the door’s path that you might not notice, a force adjustment that’s set too sensitive, a logic board fault in the opener, or a limit switch problem. These require professional diagnosis.

Do sensors need to be replaced when I get a new opener?

Not always — but it depends on compatibility. When Same Day Garage Door Service installs a new opener, we test your existing sensors first. If they’re compatible and functioning, we reuse them. If not, we replace them as part of the installation.

Serving Sammamish, Bellevue, Redmond, and the Eastside

Same Day Garage Door Service has diagnosed and repaired thousands of sensor issues across Sammamish, Bellevue, Redmond, Kirkland, Issaquah, and the rest of the Eastside. We carry replacement sensors for all major opener brands and offer same-day appointments — so you’re not stuck with a door that won’t close.

Call us at (425) 333-7171 or visit our contact page to schedule. You can also read more about our garage door repair services across the Eastside.