Garage door opens by itself?

Most "ghost" openings are not ghosts. The simplest cause is a stuck button. Wall consoles get sticky from dust, condensation or a dying switch, and a shorted wire can mimic a button press. Remotes get pressed on a visor, in a pocket, in a bag or under a seat cushion. A stuck remote can send repeated signals and sometimes even wears the batteries down fast, which is a clue.

Older openers that use a fixed code with dip switches can be triggered by another remote with a matching code. In a dense neighborhood that is uncommon but real. Modern openers use rolling codes, so a stray signal is much less likely. If your opener is the older switch kind, the fix is replacing it rather than chasing the code. Radio noise from nearby equipment can also cause strange behavior on some systems.

Smart add-ons are another place to look. An app, a scheduled routine, a geofence that thinks you are home, or a shared account with a family member can all open the door. And a failing logic board can trigger on its own, usually after a surge or moisture, with random timing that does not match anyone's habits. Pay attention to when it happens and who or what was nearby.

A stuck button or a bad remote is a small fix. An older fixed-code opener is a good candidate for replacement, because newer units are more secure and also meet current safety standards. See garage door opener installation when that is the better path.