How to fix a garage door sensor that is red?

Fixing a garage door sensor that shows red depends on whether the red light is solid or blinking and what brand you have. On Genie and Overhead Door systems, a solid red is normal for the sending sensor and means it has power. If that red light is blinking, you have a power or wiring issue. Start by unplugging the garage door opener motor unit from the ceiling outlet for 30 seconds to reset the logic board. While it is unplugged, inspect the low-voltage bell wire that runs from the motor head to the sensors. Look at the terminal screws on the back of the motor unit, usually white and gray wires, and make sure they are tight and not corroded. Follow the wire down the wall and check for staples that are too tight, cuts, or rodent damage. At the sensor itself, check that the wires are securely connected under the screws. Clean the lens with a soft dry cloth to remove dirt. Reconnect power. If the red light stays blinking after that, try disconnecting both sensors from the motor head and then briefly reconnecting a new sensor pair to see if the fault is in the wire run or the sensor itself. If the wiring is good, replace the sensor pair, as they are sold together and the internal board has likely failed from moisture or age.