Citroen C4 sat nav failure , radio problems eco doesn’t work

You want to check your battery voltage before starting the car after lying overnight . A low battery can cause these type of problems . May only need charging but possibly replacing . Alternatively get the battery LOAD tested

Thankyou for suggestion - the battery is good. The radio and satnav goes on and off throughout a journey. I checked the airial for water ingress all ok.

Despite the battery starting the car you cannot know the overall condition without checking the voltage or testing . Once driving the alternator will replenish as able , dependent on what electrical components , lights , heater , wipers etc are used .