Buy links on this page go through our /go/ redirects to the manufacturer or retailer. We earn nothing from them today; that may change. Disclosure.
In short
Flashing opener lights with a door that won't close almost always point at the safety sensors. Chamberlain says that when the sensor beam is blocked, the door reverses and the opener lights blink 10 times (or you hear 10 clicks on models without lights). LiftMaster's manual says that if the beam is blocked or misaligned while the door is open, it won't close.
Maker parts (check your opener's manual first):
LiftMaster 041-0136 safety sensor kitChamberlain 041B0873 sunblocker kitWhat to check, in order
- Look at the sensor LEDs. Green blinking means blocked or misaligned; either LED off means no power to that sensor. See the light chart.
- Clear the path and realign. See blinking green.
- Check the wiring. LiftMaster's diagnostic table lists a short or reversed sensor wire for a door that won't close while the lights flash. Inspect the wire at all staple and connection points.
- Look for something on the door that crosses the beam as it closes, per LiftMaster's table.
Closing the door for now
Chamberlain says that if a sensor isn't working, the door can still be closed by pressing and holding the wall door control until the door is fully down. Watch the door the whole time and keep people, pets and cars clear. Get the sensors fixed before going back to the remote.
Diagnostic codes
Some LiftMaster openers show a diagnostic code as a set of flashes. Your manual's diagnostic chart says what each code means. In the 98022 manual, the sensor-related codes point to a short or reversed sensor wire, or to sensors that are misaligned or were momentarily obstructed.
Never bypass the sensors. LiftMaster's manual says the safety reversing sensor is a required safety device that must not be disabled, and the beam must be no higher than 6 inches above the floor. After any fix, test it: the door must reverse when the beam is blocked.
How we work: the flash behavior and hold-to-close workaround come from Chamberlain Group support; the diagnostic table comes from LiftMaster's 98022 manual. We don't test garage door openers ourselves. Sources are listed below.
Questions people ask
Why do my garage door opener lights flash?
Chamberlain says the lights blink 10 times when the safety sensors stop the door from closing.
How do I close the garage door if the sensors are bad?
Chamberlain says press and hold the wall door control until the door is fully closed. Watch the door the whole time.
Can bad wiring stop the door closing?
Yes. LiftMaster's diagnostic table lists a short or reversed sensor wire for a door that won't close with flashing lights.
Sources
Last checked Oct 23, 2026. Details come from LiftMaster's 98022 manual and sensor kit page and Chamberlain Group support. Never disable the sensors; test them after any fix.
