Anyone had this fault? When trying to start the engine”key not recognised “ shows on the dashboard? It will only go away when I exit the car and lock and unlock with the remote. The battery in the fob is quite new.

If it was one off wouldn’t worry, it is simply didn’t authenticate.  Could be all sorts of reasons signal got blocked : someone else nearby pressed a button on their key, another device (mobile or Bluetooth etc) sent a signal at same time, key was partially shielded etc.

 

Sort of electronic equivalent of glancing around a hall full of people and not being sure that you definitely saw a specific person.   If unsure rather than let car be driven away (possibly by a thief which dodgy clone), pause and redo the checking again from scratch.

 

But if it keeps happening then possibly faulty key or car receiver.