I have a 2007 Citroen C4 2lr diesel. Every couple of months it won't start, it just clicks when ignition is turned. The battery is not flat and all connections have been checked. I have to carry a jump starter around with me in case it happens. When leads are connected it starts first touch. Can't take to garage because it never happens then. Fantastic car, just this annoying problem. Anyone come across this problem? Cheers, Les.
If the car starts with a jump pack then there is a problem with the battery, connection or something draining the battery. It can't be anything else.
I would start by having the battery 'drop tested' where the battery is put under a high load and tested.
Is there always a set of circumstances that leads to it not starting? Maybe after being left for a couple of days or after driving at night(the headlights being on) etc.
A common fault with Peugeot/Citroen vehicles causing a flat battery is the BSI or BCM unit (the fuse boxes located in the interior and the engine bay) the BSI is most likely to cause a flat battery as sometimes it fails to go into sleep mode or it fails to give the command that makes the rest of the ECUs go into sleep mode.
I would take the car to a independent Peugeot/Citroen specialist or a specialist auto-electrician to have the BSI software updated at the same time they could have a look inside at the PCB to check for dry solder joints, water damage etc.