This is a common question in any garage door FAQ. Federal law requires that your garage door be equipped with an auto reverse safety feature to prevent a door closing on obstructions including people or pets. A garage door opener has a sensor that detects resistance when it’s closing and automatically reverses when it does.
There are several things that can trigger the auto reverse. The obvious reasons include an object blocking the door like a bicycle or a box. People or pets would also cause the door to reverse (thankfully). In addition to that, if there are problems with your doors track alignment or other door system faults that cause resistance when closing, the opener may interpret that as an obstruction and initiate an auto reverse. Finally, a faulty opener controller board could also cause unpredictable behavior. If there are no obvious obstructions and your door reverses for unknown reasons, even sporadically, it’s best to call for service to avoid any safety risks.