Are both lights on the garage door sensors supposed to be green?

Both lights are generally not supposed to be green at the same time on the majority of residential garage door openers in North America. Understanding the color code helps you diagnose problems quickly. On LiftMaster, Chamberlain, Craftsman, and Stanley systems, the sender unit that emits the beam will have a yellow or amber LED that stays solid when it has power. The receiver unit on the opposite side will have a green LED that stays solid when it is aligned and successfully receiving the beam. If the green light is blinking or off, it means it is not aligned, the beam is blocked, or there is a wiring fault. Some Genie and Overhead Door models do use green for both sides, or one red and one green, so you should always verify with the label on your sensor or your owner's manual. If you have one yellow and one green and both are solid, your sensors are normal. If you have two greens on a system that should be yellow/green, check that you have not accidentally installed two receiving sensors from two different kits.

Both lights on garage door sensors are not supposed to be green on the majority of residential garage door opener systems in the United States. The typical configuration uses two different colors to make troubleshooting easier. One sensor is the sender or emitter, and its job is to send an infrared beam across the garage opening. That sender sensor usually displays a solid yellow, amber, or orange light to show it is powered and transmitting. The other sensor is the receiver or detector, which must see that beam. When it is properly aligned and receiving the signal, it will show a solid green light. So the correct normal state you are looking for is one solid yellow or amber light and one solid green light. If you see two green lights, it could mean you have a Genie brand opener, as some Genie models use a solid green for the sender and a blinking or solid green for the receiver, or you may have mismatched sensors. If you are seeing green on both on a LiftMaster or Chamberlain, check your manual because one side may be wired incorrectly or you may be misreading a dim amber light as green.