How do I keep garage door sensors working?

A monthly habit does most of the work

Safety sensors rarely fail on their own. Most problems come from a bump, dirt, sun or a pinched wire, and all of them show up in a quick monthly check. The CPSC recommends that you inspect the garage door and the garage door opener every 30 days to make sure they are working properly,^[1] and LiftMaster's maintenance list puts the same job under every month: "Test the safety reversal system."^[5]

The monthly check

Do it with the door closed and nothing parked in the way.

First, wipe both lenses with a soft dry cloth. Genie's advice is to wipe the lens with a clean cloth and make sure the beams are parallel from each other.^[4] Spider webs, dust and condensation are the usual lens problems, and a wet garage in a Virginia summer collects all three.

Second, look at each sensor's light. A steady light on both is normal on many models; a dark or flickering light on one means the sensor needs attention before it fails on a busy morning. Your manual says what each light means for your brand.

Third, test the reversal. The CPSC says to place a 2x4 on the floor of the garage in the door's path, and if the door does not properly reverse when striking the 2x4, the opener should be disengaged until it is adjusted, repaired or replaced.^[1]

Keep the sensors from getting knocked

Bumps are the most common cause of a misaligned sensor. Keep bikes, bins, mowers and hoses out of the zone near the door, and park so the car does not swing close to a bracket. If a sensor keeps drifting, snug its bracket screw or wing nut and re-check the aim, as in how to align garage door safety sensors.

Keep the sun out of the receiving sensor

Sunlight carries infrared light, just like safety sensors do.^[3] If the door fails to close only at certain times of the day, shade the receiving sensor. On Genie units, the green LED sensor should be positioned out of direct sunlight.^[3] A simple shade is to build a box around the green LED sensor lens or tape a piece of cardboard to the top of the sensor, taking care to avoid blocking the actual sensor.^[3] On other brands the receiving sensor is marked in the manual.

If you have two doors with two sets of sensors, Genie says to avoid crosstalk by setting the red LED sensors back-to-back or the green LED sensors back-to-back.^[3]

Look after the wire

Walk the thin wire from each sensor toward the opener once or twice a year. Look for slack that could snag, wire hanging where a ladder or bike could catch it, and staples that squeeze the insulation. Genie's troubleshooting chart warns that staples can cut insulation and short wires.^[2] If you see a nick, do not tape it and hope. A damaged sensor wire is a job for a technician.

Replace old sensors before they fail

Sensors do wear out. Genie notes that a sensor may have become defective and that it may be time to update your Safe-T-Beams.^[4] If one is cracked, yellowed or has a lens that will not stay clean, or if a light has gone dark, plan a replacement rather than waiting for the morning it will not close.

Stop and call a pro if

• The reversal test fails. Disengage the opener and have it serviced.^[1]
• A sensor light stays dark or keeps flashing after cleaning and re-aiming. The sensor, the wire or the opener may have failed.
• The door is heavy, uneven or binds by hand. The CPSC says that doors which are not balanced, or that bind or stick, should be serviced by a professional.^[1] Do not touch springs or cables.
• You find damaged wire or need a replacement sensor connected. That is work at the opener's terminals.

Getting help in Virginia

If the door will not close and the opener light blinks, read why the door will not close when the opener light blinks. Loclis lists local garage door businesses under garage door repair, and there are more garage door answers.

When you are ready, describe the job and local pros quote it.