It hits the floor and comes back up. A travel limit, most likely
The door is doing what it is designed to do when it thinks it has hit something. Annoying, not dangerous, unless you defeat the safety to stop it.
What is probably happening
- The down travel limit is set too far. The door presses into the slab, the opener reads that as an obstruction, and reverses. Common after a new bottom seal or a new slab.
- The down force setting is too sensitive for a door that has stiffened with age or cold.
- Something is under the door: a rock, a lump of ice, a warped seal.
Do this in the next five minutes
- Sweep the threshold and check the bottom seal for a lump or a fold.
- Find the limit and force adjustment screws or buttons on the opener. They are labeled. Back the down travel off a quarter turn at a time until the door seals without reversing. The manual for your model is online under the model number.
- Then run the safety test: with the door open, lay a 2x4 flat on the floor under the door and close it. Chamberlain: the door must reverse on contact with a 1.5 inch object. If it does not, stop and call.
- Repeat the 2x4 test monthly. Chamberlain says monthly and after any adjustment.
Do not
- Do not crank the down force to maximum so the door stops reversing. That is the setting that decides whether the door reverses off a child. The CPSC's advice since 1983 is to adjust the reverse mechanism for sensitivity per the owner's manual.
- Do not disconnect the sensors to get it to close.
Who to call
A garage door technician, if adjustment does not hold
If the limits will not hold, or the door fails the 2x4 test after adjustment, the opener or the door balance needs a professional.
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What it should cost
$100 to $500
Opener repair range, average repair $265
Source: Angi, garage door repair cost, updated August 2026. View source
National published range, not a quote for your job. The full cost table for this trade is on the garage doors page.
Ask this contractor, on the phone, before anyone comes out
Tap each one as you ask it.
- Is the door balanced with the opener disconnected, or is the opener compensating for a tired spring?
- Will you run the 1.5 inch reversal test and show me before you leave?
- What is the total including the call fee?
End the call if
- A technician who fixes the reversing by turning the force up and does not test with a board.
- A rebuild package for a limit adjustment.