If your garage door opener doesn't open or close properly, the culprit is usually the opener sensors. An infrared beam sends a signal to one sensor to open the door, and the other sensor receives the signal to close the door.

Safety sensors are commonly located six inches from the garage door base.The safety sensors activate in case the beam gets damaged to prevent the door from accidentally closing. Here are some tips to replace garage door opener safety sensors.

Prepare to Work

For this project, you need:

• work gloves
• safety glasses
• step-ladder
• rag
• carpenter's level
• pliers
• adjustable wrench
• screwdriver
• elastic cord
• wire nuts
• pin snips or wire cutters
• wire strippers
• new sensors

Before replacing the sensors, try to clean and adjust them. Set a step-ladder on a level surface and verify the garage door opener sensors aren't blocked by debris. Clean dust and debris with a rag, then try the opener again.

If cleaning fails to repair the sensors, rotate the small nuts on the L-bracket in small increments until you see an indicator light. Try the opener again. If they still fail to smoothly open the door, proceed to replace them.

Remove the Old Sensors

Buy new sensors from a home improvement center or hardware store. Climb the ladder and disconnect the opener's power cord from the ceiling. You may need to remove the lens cover from the motor head on some models.

Disconnect the wire nuts, and use pin snips or wire cutters to cut the wiring loose. Cut wires an inch from the sensor to leave slack for the new sensor.

Install the New Sensors

Place the new sensors in the same position as the old sensors. Don't tighten the fittings, since the sensors may need adjusting. Strip about 1/4 inch insulation from the wires on the new sensors.

Insert the sensors in the L-bracket, and secure the wires where you cut the old wires with wire nuts. Place the cord on one sensor, and get an assistant to hold it down for you. Extend the cord to the other sensor, and check for evenness with the carpenter's level.

If the bubble on the level isn't centered, keep adjusting the sensors until they are even. Once the sensors are even, tighten the fittings with the screwdriver, and repeat the cord test.

Set a a box or similar object under the door to test the opener sensors. The door should remain open upon detecting the object. If you don't trust your skills, or the opener fails to work, contact a garage door repair service such as Duncan Door Service Inc.