Garage Door Sensor Lights: Green vs. Yellow Explained
On most garage doors, the two safety sensors near the floor have different colored lights for a reason: one eye sends the beam, the other receives it. The sending eye usually glows a steady amber or yellow whenever it has power, while the receiving eye glows steady green only when it's perfectly lined up with the beam unbroken. So a solid yellow and a solid green light is good — your door should close. If the green light is off, dim, or flickering, the sensors are misaligned, dirty, or blocked, and the door will refuse to close.
Step by step
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1
Know which light is which
Look at the two small sensors mounted about six inches off the floor on each side of the door. One is the sender (its LED is almost always steady amber/yellow when powered) and one is the receiver (steady green when aligned). Yellow is just a 'power's on' light — green is the one that actually tells you the door will close. Don't panic about the yellow one; it's supposed to stay on all the time.
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2
Read the green receiving light first
Steady, solid green = good alignment, beam unbroken, door will close. Green that's off, dim, or blinking/flickering = the receiver can't 'see' the sender's beam. That's your real problem, and it's almost always why a door starts to close then reverses back up.
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3
Clear the beam path and wipe both lenses
Move any trash cans, hoses, leaf piles, or boxes near the floor on both sides. Then gently wipe each sensor's little lens with a soft, dry cloth — dust, cobwebs, or condensation scatter the beam enough to kill the green light. Skip harsh cleaners; they can cloud the plastic. Re-check the green light after.
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4
Realign the sensors until green is solid
If green is still blinking, a sensor got bumped out of aim — by a basketball, a broom, a pet. Loosen the wing nut or bracket just enough to swivel it, and nudge it slowly until the green light stops blinking and glows steady. Both sensors should sit at the same height and point straight at each other.
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5
Check power and wiring if a light is fully dead
No yellow AND no green on one sensor usually means it's not getting power. Look for a chewed or pinched wire, a loose staple, or a connection that's pulled away from the opener terminals. A completely dead sensor that has good wiring has likely failed and needs replacing.
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6
Test the door once both lights are solid
With steady yellow on the sender and steady green on the receiver, press the wall button and watch the door close fully. If it goes all the way down and stays down, you're fixed. If it still reverses with both lights solid green and yellow, the issue has moved past the sensors — likely the close-limit setting or the opener itself.
When to call a pro
If both lights are out completely (no yellow and no green), if a sensor light stays dead after you've checked the wiring, or if the door still won't close once both lights are solid, call a pro — you may have a wiring fault, a failed sensor, or an opener logic board issue that isn't a DIY fix.
Call (888) 290-7421Frequently asked
Is yellow on a garage door sensor bad?
Usually no. On most openers the yellow (amber) light is the sending eye, and it stays steady yellow whenever it has power — that's normal and means it's working. The light to worry about is the green receiving eye. As long as yellow is solid and green is solid, your door should close fine.
Why is my garage door sensor light blinking or flickering?
A blinking green receiving light means the two sensors aren't seeing each other — they're misaligned, the lenses are dirty, or something is breaking the beam near the floor. Clear the path, wipe both lenses, then gently nudge the sensors until the green light glows steady instead of blinking. That fixes it the vast majority of the time.
Both sensor lights are off — what does that mean?
No light at all on one or both sensors usually points to a power or wiring problem, not just alignment. Check for damaged or loose wires running back to the opener. If the wiring looks intact but a sensor stays completely dark, that sensor has likely failed and needs to be replaced — an inexpensive fix for a pro.
My sensor lights are both solid but the door still won't close — now what?
If yellow and green are both steady and the door still reverses, the sensors aren't your culprit. The next suspects are the opener's close-limit (travel) setting, a stuck wall button, or a track or spring problem. If you're not comfortable adjusting the limit screws, a local pro can usually diagnose and fix it same day — call (888) 290-7421.
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