Adding some information about possible problems with this sensor if anyone will dig out this thread (as I did).
In my case sensor had intermittent failure. Once a few or a dozen minutes of printing it reported no filament (== no "low" pulses were sent). Then after 1-2 days it died completely.
It turns out that when I mounted it using one of thingiverse mounts screw pressed a tiny bit on the side of connector causing it to rip ground path directly under connector. That caused no power on C145 chip (well, there was ~1.2V there).
The fault was only visible under microscope and even then it wasn't immediately obvious/visible because main pins were soldered fine. Only one pin on the side (the mounting one) was ripped (and was up over pcb a fraction of mm).
