LiftMaster garage door opener: Code 1-1: 1 UP flash, 1 DOWN flash
One of the safety sensors is blocked, out of line or unplugged, or its wire is broken. The door starts to close, then reverses.
Applies to: LiftMaster and Chamberlain Security+ 2.0 and Security+ 3.0 openers with UP and DOWN arrows; codes 3-5 and 5-5 only on the wall-mounted jackshaft models 8500W/RJO70, 98022/RJO101 and 98032. What you see: the UP and DOWN arrows, 1 UP flash, then 1 DOWN flash.
Covers Chamberlain openers too: the two brands share one published table, so each code has one page here.
What LiftMaster says to do
This is a safety-sensor code. The sensors stop the door closing on a person, a pet or a car. semiatic repeats only LiftMaster’s own alignment and cleaning steps; nothing here tells you to work around the sensors, and LiftMaster’s wiring checks are on its own page.
- LiftMaster says to remove anything blocking the invisible beam between the two sensors.
- LiftMaster says to look at the two sensor lights: if the green light is off or blinking, align the sensors so they point at each other.
LiftMaster’s page then goes on to checking the sensor wires at the opener and further wiring checks if the code will not clear.
LiftMaster’s safety line: “Never adjust or loosen the door’s springs, cables, pulleys, or brackets yourself, they’re under extreme tension.” Where a spring, cable or balance problem shows up, its page says to stop and contact a local garage door professional.
No repair advice of our own. The steps above are only LiftMaster’s, as its page states them; semiatic gives no repair instructions of its own. For anything beyond them, LiftMaster’s page and a trained door technician are the authority.
Source
LiftMaster’s own help page, read on the date shown.
- Chamberlain Group Support (LiftMaster and Chamberlain): Garage Door Opener | Diagnostic Codes and UP/DOWN Flashing Lights — LiftMaster and Chamberlain Security+ 2.0 and Security+ 3.0 openers with UP and DOWN arrows; codes 3-5 and 5-5 only on the wall-mounted jackshaft models 8500W/RJO70, 98022/RJO101 and 98032. support.chamberlaingroup.com Checked 2026-09-29.
Other LiftMaster codes
Find a code by which light flashes and how many times, on any maker’s opener →