It’s snowing hard here on the slopes of Epsom Downs. Driving back from my son’s Wimbledon home this morning, it started to sleet (not hard snow like here) and I got a warning that ‘Fault - Front Assist Inoperable’.

 

I’m guessing (hoping) that the sensor was just obscured by the sleet, but it doesn’t bode well to have a warning sensor not operating at just the time when you are likely to need it most!

It's normal, either there's a build up of snow on the sensor or the snow is so heavy that the radar signal is getting dissipated. 

Driving in sleet, snow and rain is when the driver wants to be to try taking as much control as they can of their vehicle allowing for the ESP, TC/ASR etc and not trusting to much of the tech the car has which was designed by someone not in the car with you.