Hi, I have a 2018 Ford S Max and this morning when I tried to drive off a warning came up, parkbrake malfunction service now, and the parkbrake was jammed on.  I tried switching the car on and off a few times and the warning went off and the hand brake released itself, I drove to my work and when I parked it back up ive left it in gear and not put on the parkbrake (its on flat ground) 

It did have the same warning ping up yesterday when I stopped and it was very snowy, I skidded a bit so wondered if that had anything to do with it, but the warning went off and didnt come back on again on my journey yesterday.  It has been quite cold here well -5 to -8 maybe through the night. 

Now my car did this last year and my man is a mechanic so did manage to unjam it a few times with his diagnostics machine and in the end he replaced 2 bits on the brake (calipers or something maybe) this did fix it and its been fine for a year, it may be a coincidence but it was in the winter last year it did this as well.  The repair did end up costing a bit and I dont fancy having to fork out every winter !  

Has this happened to anyone ?  Ive tried google and can see some people mentioning the battery, this was replaced last year as well Im sure. 

Could've been frozen mechanism, especially if it was power washed recently, check and lubricate rear mechanisms.