HEY GUYS I NEED HELP so i recently bought a 2011 xf ,5 liter supercharged , i woke up having battery problems i got a jump start , then the car shut of on me whilst driving , it could not restart i went and buy a new battery it started then shut off again i get the code

P0851the selector switch will not raise up ,

 

You'll need to do some diagnostics for us. Firstly what voltage is the battery when the car is off. And what voltage when it's on?

My starter guess would be weak battery (note that new batteries are rarely fully charged), alternator not functioning properly or an earth grounding issue between battery or circuits and the bodywork