I have a Marantec garage door opener. I can provide the model number if necessary. It seems like 50% of the time the sensors are not operational. I can still close the door by holding down the button. It's not related to the sun because it happens night and day and it also has a sun shield. When the sensors aren't working, the lights on the eyes are completely out. If I click the button, I just hear a click on the opener.


3 Answers 3


if sunlight on the sensor isn't causing the issue, then the problem is either bad opener, bad wiring or a bad sensor.

when the sensors are not working, use a multimeter to test the voltage put out by the opener. if that's not right, then you might have a bad opener.

next i would try disconnecting all of the wires at both ends, cutting off the exposed conductor and stripping the wires fresh, then reconnecting. make sure to thoroughly clean any corroded terminals.

if neither of those are the issue, then you need to decide which is easier for you: replacing the sensors or replacing the wiring. do one of those, and if that doesn't fix it then do the other.

  • Doh, I spent too long looking for the humorous comment that you beat me to a real answer. +1
    – BMitch
    Jun 17, 2011 at 16:18
  • How do I test the voltage put out by the opener? The voltage put out to the sensors? What two points do I test, wire out and ground?
    – kakridge
    Jul 6, 2011 at 23:46
  • on my opener, there are three screw terminals for the sensors. one that supplies power to the sender and the receiver, one that senses the signal from the receiver, and one for ground/common. test between the power and ground.
    – longneck
    Jul 7, 2011 at 12:37
  • Thanks. Every time I go try to test it, the darn thing is working. Whenever I'm leaving in a rush and can't test, it's broken. Probably a correlation somewhere.
    – kakridge
    Jul 7, 2011 at 18:53
  • you should test it while it's working so you know what the voltage should be.
    – longneck
    Jul 7, 2011 at 20:48

The solid 20 or 22 gauge wire that comes with most openers is junk - replace it with some decent stranded wire.

I spend days trying to track down intermittent problems, and ended up replacing it all - I haven't had a problem since then.


Make sure the sensors are aligned. Try bending the brackets slightly so they point directly at each other.

  • They are definitely aligned and there is quite a bit of leeway before they get out of alignment. It will literally not work at night and then be working in the morning, so I know it's not an alignment issue.
    – kakridge
    Jun 18, 2011 at 1:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.