New to me P400e, have a strange issue with key fobs. First port of call, I swapped the batteries out for brand new

Car has two keys, one is completely and utterly dead as far as I can see and will not lock/unlock the car. The second key does unlock/lock but sporadically! Sometimes I can stand next to it pressing lock or unlock and nothing happens. Then try keyless and it works, sometimes that won’t work either but then the fob does. If I stand further away (10ft) it won’t register at all.

Also getting smart key not detected messages, happened twice but always starts and does not do this every time.

I’m suspecting 12v batteries are likely, they both look original and car is 6years old now.

Any ideas?

Are they genuine keys, as in is the pcb as per original or are they Chinese versions and the KVM module has been cloned? I came across a similar problem and it was due to non original keys and a modified KVM. L405 SV Autobiography LWB SDV8, finished in Aston Martin China Grey by ETO division.

How can I check?

I didn’t see anything that made me think they weren’t genuine when I swapped batteries

Are they CR2032’s in the fob?
Buy some new Duracell and polish them with a clean tissue as you remove the plastic film to remove any grease, fingerprints etc.
Mike. G reg 2.5VM Vogue Portofino red 1991- 1999
V reg 2.5td P38 Rioja red 1999- 2006
53 reg td6 Vogue Oslo blue 2006- 2015
11 reg 4.4 TdV8 Vogue SE. Baltic blue 2015- date.
https://www.fullfatrr.com/forum/topic56162...tty+affair

I've found that cheap 2032 button batteries just dont seem to last / work as well as the expensive Duracell type brands. Find for small tv remotes etc, but car keys etc seem to be more sensitive to how good the battery is.

Also, does the manual not mention anywhere about holding the keys up to the steering column to re-sync the keys sometimes. . The sensor is around that area I think. V8 or else ...

I used the sleeping batteries JLR sent, which a mere couple of hours previously worked in the older L405 I had before.

I trickle charged the car yesterday and my CTEK gave me a red light at stage 5, so I’m going to swap the aux battery to see if this sorts it. If not looks like the main starter battery might be past its best. Both appear to be 6 years old so about time anyway.

I had to hold the keys up to the dash to start it when the error was present. I’ll double check the manual on syncing

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