Safety: Garage doors are heavy and spring/cable systems can be under significant tension. Do not loosen or disassemble high-tension hardware unless you are qualified to do so.
Common Sensor Symptoms
A door may begin closing and reverse, refuse to close from the remote, or show a flashing indicator when the safety system detects a problem.
Simple Things to Check
Make sure nothing is blocking the opening and that the sensor area is clear. Avoid bypassing or disabling safety devices.
When It Is Not the Sensor
Travel settings, wiring, opener controls, binding tracks, and other mechanical issues can sometimes produce similar symptoms.