LiftMaster garage door opener: Code 1-2: 1 UP flash, 2 DOWN flashes
The safety sensor wiring is probably reversed or shorted, so the door will not close.
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 2 DOWN flashes.
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’s page gives no step for this code that is repeated here; the meaning above is what it says.
LiftMaster’s steps for this code are all wiring checks: the same wire colours to the same terminals at the sensors and at the opener, and the wire inspected along its run for staples, nails or cuts.
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 →