If your door is not going DOWN from the open position at all, as in no movement, this is the first article to read!

Absolute Quality Garage Door is committed to providing the finest customer service in the area. Keep reading to troubleshoot your sensor issues!

On Liftmaster and Chamberlain machines the light bulbs in the opener head (if working) will flash on and off. Even if the light bulbs are burnt out, you can often hear a repetitive clicking sound from the opener head. On those brands of machines this is a CLEAR indication that your sensors are out of alignment. Note that some Liftmaster/Chamberlain models will also flashing flash its lights and click if the opener lock (locks out transmitters and keypad transmissions) is engaged, but that is a rare occurrence. There are other possibilities for doors not closing, particularly the sensitivity being set too low or having a dumped cable, in these cases the opener will often move a little ways down then reverse and go back to full open position.

Misaligned sensors are one of the most common day to day problems that I receive calls about. Opener manufacturers started including a safety reversal system on their products in the early to mid 90’s. While these sensors do provide a great safety feature, they tend to get bumped out of alignment by the large amount of stuff that some tend to pile into the corners of their garage. Fortunately they are quite easy to fix! I dislike having to charge people for such a simple service call. Hopefully with this blog post I will be able to show you how to fix the issue for FREE!


Different manufacturers have different looking sensors. The general concept is consistent across the board. The sensors “shoot” an infrared beam between a sending sensor at the bottom of the vertical track on one side of the door to a receiving sensor on the bottom of the vertical track on the other side of the door.

The standard location of garage door opener safety sensors (Red Ovals)

On older Liftmaster and Chamberlain machines both LED lights on these sensors may be green. Some sensors are labeled close to where the wire goes into them as sending or receiving.

On newer Liftmaster and Chamberlain machines you should have one amberish LED (the sender) and one green LED (the receiver)

Liftmaster Sending Sensor (Yellow or Amber LED) Should always be on. If not, you have bigger issues.

Liftmaster Receiving Sensor (Green LED) (This one is functioning and fully aligned since it is lit!)

On Genie machines you may have a green and a red, or two red LED lights.

Regardless of brand or age you should have at least one LED lit at all times. Otherwise, a wiring, bad sending sensor, or circuit board issue is present. If you do not have ANY LED lights on at all, I would recommend calling a professional. Things can get a little complicated in that case. Tracking down a bad wire or circuit board requires patience and skill.

If you have at least one LED lit; Congratulations! You have found the sending sensor! It is the one with the lit LED.

For Liftmaster and Chamberlain machines almost every generation has included a bracket mount with a wingnut to adjust where the sensor aims. As long as the sending sensor is reasonably pointed at the other side of the door, you should proceed to the receiving sensor(green), loosen the wingnut, stay out of the path between the two, and move it around until the LED lights up, indicating that it is once again receiving the signal. Tighten the wingnut while the LED is still lit. Then wiggle the whole bracket a bit, make sure the light stays solid. Speaking of solid lights… it is not uncommon for me to go to a call where the door sporadically reverses, and has been doing that for some time. The receiving sensor may APPEAR to be fairly solid until you take a close look at it, the LED will be barely fluctuating in brightness, this indicates a close alignment, but not quite there! Always adjust until you get a nice solid light!

For Genie and some other models adjustment of the sensor aim must be accomplished by bending the metal mounting brackets… One of the reasons that I so enjoy working with and installing Liftmaster/Chamberlain products is the amount of forethought put into the design. Genies and many other opener brands simply lack that at EVERY turn. That quality Liftmaster design projects itself into the longevity of service and overall usability of the machines.

Hopefully I have successfully guided you to fixing your sensor issue. If not, please give me a call at 970-820-0218 or email me. If you are close to Brighton, and the problem really is with the sensors, it will likely not take me long to fix it. In those cases, I frequently charge a reduced service call. No promises, those reductions are based on distance, time, and difficulty of the job. Thank You.