When I first bought mine, it was triggering every time someone turned left in front of me. It turned out that it was in 'Country mode'.
Once I switched it to city mode, it stopped giving me false positives.
It also gave me a bit of a fright when a dust devil crossed the road and was dense enough to trigger the system.
However, on the good side...
... A driver in a four wheel drive changed lanes so aggressively that he lost control of his car.
The car spun end for end, crossed two lanes, and ended up in my lane, facing me.
The FCM triggered the brakes before I could get my foot onto the brake pedal.
I was very impressed with the system when that happened.