Mine died after about 1 month. I suspected the photocell was bad because it worked in test mode. I covered up photocell with several layers of tape as an experiment and it still didn't come on. Funny - I called DESA in Bowling Green, KY who makes the unit and they said to put some tape over the photocell and if that helped, to use the diffusers.
Today I purchased a replacement motion sensor from Lowe's and replaced the one that was on the lights and will let you know how long it lasts. It's same model number, but maybe they ran a few bad batches.
I would be willing to pay a bit more for something that lasted. They didn't even use stainless steel screws on the light housings. I'll end up replacing those because they're turing the lights brown from rust stains. Not that anyone would notice except my own anal retentive self.
Will let you know how long the replacement sensor unit lasts.