Hello All
The parents Jag XF 2008 2.6 v6 diesel auto(think its 2.6)

Anyway
Recently we had an issue with the jag deciding it was not gonna start after a short run. Break down came - diagnosed a flat battery, jump started and off it went to the garage. To go an behold it went flat again
So with the ""dead battery"" cause been rectified with a new battery

This worked grand, except it now has the constant warning of alternator issues (red battery on screen)
The Alternator is working, as there is 12.6v off
14v at idle speed
and over 13.5v with load, so its working in that sense

Since its been drivable - its been driven daily and not been an issue since bar the warning

Till tonight
Nipped down to the shops - he's then come back to the car
No responce from the key - car wont open
So spare key fob brought down, even that key wont work

So we pop the emergency key out and pop the cover and open the door
Go and behold - the lovely alarm is going off....
The fobs STILL wont work
We tried bunging the key in the Slot under the dash - to try and deactivate the alarm, except the dash board keeps saying Check Key
Nothing happens except the alarm is still going off

In the end the recovery people have been called again! they are baffled

The car wont start even with key in slot (check key message on dash)
The alarm is always going off every time you open the door - yet we have the freaking key

I really need the WWW of Jag lovers to really help out here!
I'd like to blame the car forgetting both of its keys (ecu?) but there MUST be something simple then that?

Ziggy

 

It's a 2.7.

Most obvious cause is a bad battery. Have it load tested and replaced if it fails that load test. A voltage test is useless.

A battery is good for around five years. After that you are lucky to have it last.

Modern cars display all manner of strange symptoms if the battery is bad. Get it checked carefully by a knowledgable professional before doing any more work on this car.

 

it had a brand new battery when garage diagnosed weak battery
so its brand new
the alternator light is on but it is charging

ziggy

 

I'd say check the battery drain. Most have had software upgrades to eliminate the battery drain from the infotainment system. It could explain all your issues. The battery may be too low to recognize the keys. Try charging/jumping it and see if you can get the keys to work again.