How to know what the flashing LED
lights on your Chamberlain, Craftsman, or
Liftmaster garage door opener mean.

The Chamberlain, Liftmaster & Craftsman garage door
openers have a built-in diagnostic indicator that will
assist you in troubleshooting your garage door opener.

  There is a LED light next to or near the smart button (programming learn button) on the outside of the motor cover up above the antenna. On the garage door opener pictured below the LED light is between the square purple smart button and the purple antenna wire. The LED functions as a diagnostic indicator by slowly flashing a failure code continually every eight seconds until the fault is corrected, the garage door opener is reset, or the necessary parts are replaced.

Liftmaster garage door opener with purple smart button

  Observe the flashing LED & count how many flashes occur in a row between pauses. Then refer to the chart  below for the cause of your garage door opener not working properly. Once you have fixed the problem the opener will reset itself for most issues. However note below on the last two failure codes it does require that you manually reset the opener by unplugging the unit. If you still can not get the opener functioning properly after following the steps below you should contact a local garage door dealer for a service request to resolve the problem.

# of Flashes


Auto Reset

Manual Reset


Photo-Cell totally misaligned or Photo-Cell wire open




Photo-Cell wire shorted or the wire is reversed on the terminals




Wall button (panel) wire is shorted in wall or attic




Photo-Cell sensor slightly misaligned (dim or flashing LED on sensor)




Possible RPM sensor failure or motor overheated, unplug opener to reset unit




Motor circuit failure, replace main logic board



Rapid Flashing

This is not a problem but just an indication that the opener is receiving a signal but it will not respond to an unauthorized code





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Ft Myers, FL




Liftmaster Opener LED Flashing


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