How do you reset the sensors on a garage door?

To reset the sensors on a garage door, which are the safety photo-eyes near the floor that prevent door from closing on obstruction, you need to power cycle and realign them to restore steady lights and proper function. First, unplug the garage door opener from ceiling outlet or turn off breaker for 30 seconds to cut power to sensors, as sensors get power from opener motor unit via low voltage wires, then plug back in to reset electronics. Next, check sensor lights: one sensor should have steady amber or yellow light indicating sending power, other should have steady green light indicating receiving beam. If green is flashing or off, sensors misaligned or blocked. Loosen the wing nut or bracket screw holding sensor, and adjust sensor position up, down, or side to side until green light becomes steady, not flashing, indicating beam aligned. Ensure both sensors are at same height, about 4 to 6 inches above floor, and lenses face each other directly. Tighten bracket carefully without moving sensor. Clean lenses with soft cloth to remove dirt and spider webs that block beam. Check wiring connections at sensor and at motor unit for loose or damaged wires. Ensure no direct sunlight shining into receiving sensor, which can cause false blockage. After resetting and aligning, test by closing door; it should close fully without reversing.