Sensors do burn out after a while. I had one replaced a year ago. Mine are a bit different than yours, though. Each light fixture has its own sensor. I dislike motion lights, because they go on and off all the time, for every little thing. I much prefer the ones that come on and stay on all night long. At least you can see outside if you need to.

Have you changed the lights in the fixture to LED's by chance?

Great news

Omg it was the bulb!

Your "electrician" didn't notice the bulb was burned out???

> not ALL the diodes could have died

Many LED retrofit bulbs, especially the cheap ones (which is pretty much all of them now), have all the LED chips in series across a fairly simple power supply. If one LED opens, all of them stop working, just like Christmas tree lights from 70+ years ago.

There are ways to keep a single LED failure from killing the light, but they add cost, so they don't often get implemented.

But that probably doesn't matter. The power supplies in those $2 bulbs are built with the absolute cheapest, most marginal electronic components the low-bid fly-by-night Chinese sweatshops can make. Therefore most often it's a failed power supply component that takes out your bulb, not an actual LED chip.

FWIW, I know guys who cut open failed LED retrofit bulbs and rebuild the power supplies with better components. Or sometimes salvage parts from 2 or 3 units to make one working one. Great if you have the time on your hands, I guess.

Remember when LED retrofits cost $30 or more and claimed an average life of 50,000 hours or better? Now they cost a couple of bucks, but average life is more like 20,000 hours. I saw one a while back that claimed (in small print) a 15,000 hour lifetime.

Hey, wait a minute. Now that I look at your photo, I don't see replaceable bulbs in that luminaire at all. Isn't that a premade LED-only fixture? Something doesn't add up here.

I'm a little confused about the sequence of events here. If you had asked me to diagnose the problem:

1. If the light is controlled by wall switch, ensure switch is in the "on" position.
2. Cover sensor
3. See if bulb lights. If yes, done. If no, remove bulb and test for power at fixture socket.
4. If power is present, try new light bulb and/or test old bulb in known working fixture.

Or am I missing something here.