Why does my garage door go back up when closing?

A safety system is objecting: photo-eye sensors blocked, dirty, or misaligned (the usual case), or the door meeting resistance that trips auto-reverse. Blinking sensor lights point at alignment; reversal at the same travel point suggests binding or force settings.

How do I test garage door safety features?

Monthly, two tests: wave an object through the sensor beam while the door closes (it must reverse), and place a 2x4 flat on the floor under the door (it must reverse on contact). Failing either grounds the opener until fixed.

Can I replace garage door springs myself?

Torsion springs, the wound springs above the door, are under lethal tension and are professional-only work, one of the few absolute DIY exclusions in home maintenance. Extension-spring systems at least need safety cables through them.

Why is my garage door heavy when opened by hand?

The springs, not the opener, carry the door's weight, and a door that is heavy manually has failing springs. The opener straining to lift an unbalanced door burns itself out doing the spring's job.

Garage Door Safety: Sensors, Reversal, and Springs

Page last reviewed: August 2026 · Reviewed by Harold R. Bennett, retired home inspector

The garage door is the largest and heaviest moving object in most homes, several hundred pounds traveling on stored spring energy, and its safety record was bad enough that federal rules have required automatic reversal systems on every opener sold since the early 1990s. Garage door safety sensors and the reversal system are those requirements in hardware, and they only protect houses that test them. This reference covers the two systems, the monthly tests, the spring rule, and the short maintenance list.

The two required guardians

Photo-eye sensors: the small lenses on each side of the opening, mounted low (about six inches off the floor, deliberately at child-and-pet height), projecting an invisible beam; anything breaking the beam while the door closes commands immediate reversal. Their failure modes are humble, misalignment from a bumped bracket, lens dirt and cobwebs, sun glare into a lens at certain hours, and wiring damage, and their language is the indicator lights (steady means aligned; blinking means not) plus the classic symptom, a door that refuses to close by remote but closes when the wall button is held (the hold-to-close bypass built into the standard, itself a diagnostic). Force-sensing auto-reverse: independent of the eyes, the opener monitors resistance, and a closing door meeting an obstruction must reverse on contact. Its enemies are drift and misadjustment, force settings creeping or set high to overpower a binding door, which converts the safety into a press. The two systems overlap deliberately: the eyes catch what never gets touched, the force reversal catches what the eyes miss.

The monthly tests

Two minutes, calendar-worthy alongside the GFCI buttons and detector checks: the beam test, start the door closing and wave a broom or box through the beam, expecting instant reversal; the contact test, lay a 2x4 flat on the threshold and close the door onto it, expecting reversal on contact (the standard test object, and a door that crushes or stalls on it fails). A third test audits the springs rather than the safeties: the balance test, with the opener released via the red emergency cord, lift the door by hand to waist height and let go, and a balanced door floats there, while a door that slams down or flies up has spring problems and is loading its opener with the difference. Failures ground the door to manual operation (with the release cord’s own caveat: releasing under a raised, unbalanced door can drop it) and buy the adjustment or service visit, since sensor realignment is homeowner-simple while force calibration follows the opener’s manual precisely or a technician’s meter.

The spring rule

The door’s weight lives in its springs, and the rule is absolute: torsion springs, the wound shafts above the door, store lethal energy and are professional-only work, no exceptions, one of the few flat DIY exclusions this site issues, with the winding-bar injuries of the confident populating emergency-room literature. Older extension springs, the stretched pairs along the tracks, at minimum require safety cables threaded through them so a broken spring whips along the cable instead of across the garage, a cheap retrofit worth checking for on sight. Spring life runs on cycles (the standard spring is rated around ten thousand, a decade of ordinary use), a bang from the garage plus a door suddenly too heavy is the classic break announcement, and springs replace in matched pairs by people with the bars and the training.

The short maintenance list

Yearly: rollers, hinges, and the torsion assembly’s bearings lubricated with garage-door lube (not grease-collecting heavy oils, and never lubricating the tracks, which want to be clean and dry); track fasteners and hinge screws snugged; cables eyeballed for fraying at the bottom brackets (another under-tension, look-don’t-touch component); weatherstripping at the bottom renewed when daylight shows, the garage’s air-sealing and pest line; and the photo-eye lenses wiped on the same pass. The opener’s era matters too: pre-1993 openers without photo eyes are past their safety generation and worth replacing outright, and modern units add battery backup (code in some states, sensible everywhere the power fails in storms) and rolling-code remotes. Manual-operation literacy rounds it out: every driver in the house knowing the release cord and the lift points is the power-outage plan.

The bottom line

Two safeties, two tests, monthly: the beam must reverse the door untouched, the 2x4 must reverse it on contact, and a hand-lifted door must float at waist height. Keep the eyes aligned and low, the tracks clean and the hardware snug, and leave every wound spring to the trade, because the garage door is a machine that forgives routine attention and punishes improvisation.