Garage Door Won't Close? Here's the Sensor Fix Guide

Your garage door starts closing, drops a few inches, then reverses back up. The opener light may be blinking. You try again — same result. This is the most common garage door complaint we receive, and the fix is almost always the same: photo-eye sensors.

Why Sensors Cause This Problem

Photo-eye sensors sit 4–6 inches off the ground on each side of the door opening. They emit an infrared beam across the door path. If anything breaks the beam — or if the receiver can't see the beam due to misalignment — the opener reverses, believing there's an obstruction.

The opener is doing exactly what it's supposed to do. The problem is that the sensors are reporting a false obstruction. Your job is to find out why the receiver isn't seeing the beam correctly.

Fix 1: Clean the Sensor Lenses — Try This First

A spiderweb, dust film, moisture, or dead insect on a lens blocks the infrared beam just as effectively as a physical object in the path. This is the most common cause of sudden sensor failure, especially after a period of not using the garage.

1. 1Wipe both sensor lenses firmly with a clean dry cloth
2. 2Remove any spiderwebs around the sensor housings
3. 3Check for dirt or debris in the sensor path near ground level
4. 4Test the door — if it closes, you're done

Fix 2: Realign the Sensors

Read the indicator lights on each sensor unit. A properly aligned pair shows solid lights — typically solid green on the receiver and solid amber on the sender. A blinking light means misalignment.

1. 1Identify which sensor is blinking — that's the one to adjust
2. 2Loosen the wing nut holding that sensor on its bracket (finger-loose is enough)
3. 3Slowly pivot or slide the sensor while watching the indicator light
4. 4When the light goes from blinking to solid, the beam is aligned
5. 5Tighten the wing nut firmly while holding the sensor in position
6. 6Test the door

Fix 3: Check for Sunlight Interference

Direct sunlight hitting the receiver sensor can overwhelm the infrared signal — the sensor can't distinguish the sender's beam from the ambient light. This is a seasonal problem that appears or disappears as the sun angle changes.

• ›Temporarily shade the receiver sensor with your hand while testing — if the door closes normally, sunlight is the cause
• ›Attach a small shade or sunhood above the receiver sensor (a piece of cardboard taped temporarily confirms the diagnosis)
• ›Permanent fix: a short piece of PVC pipe placed over the receiver lens acts as a shade without blocking the beam

Fix 4: Check the Wiring

If one sensor light is completely off (not blinking — completely dark), the issue is power, not alignment. Trace the wire from that sensor back to the opener:

• ›Look for wire that's been run across the floor and pinched by the door — common in garages where the wire isn't properly secured to the wall
• ›Check the terminal connection at the opener motor unit — vibration loosens these small screws over time
• ›Look for wire damage from heat, moisture, or rodent activity along the wall-mounted run

When the Door Still Won't Close After All These Steps

If sensors appear aligned and clean but the door still reverses, two other possibilities:

• ›Force sensitivity too high: The opener is reversing not because of sensors but because it detects minor resistance in the door travel. This is a technician calibration on the opener unit.
• ›Failed sensor unit: Sensors can fail electrically even when wiring is intact. If cleaning, alignment, and wiring checks all pass but the problem persists, the sensor unit likely needs replacement.