More for future searchers than current answers. Non Kessy.

One key fib stopped working one morning. Transponder part still ok, started car no problems. New battery, no joy.

Tried other fob, worked fine. Swapped batteries still worked fine. Diagnosis = dead remote part fo the key fob. 10 years old- fair enough.

Found a local locksmith who was cheaper than desler but ended up not changing the fob as he was ill/ unreliable.

2 weeks later.(tonight) leave work. Unlock OK, get to the shop for emergency rations and no locking. Aaggghh.

At home still no action at all so popped the door handle lock cover to manually lock car. And after a couple of cycles the fob is then working OK again.

Went to get "broken" fob, used it to manually lock unlock arm and disarm alarm and it too now works properly from it's buttons

So, I have a short term fix, but why is the car forgetting that the fob should unlock it.?

IIRC, when there are enough button presses while the key is out of range of the car, they will lose sync with each other. The car will relearn if you use the key in the door lock and then press the buttons.

I guess the question is, did the button get pressed repeatedly or is there a fault with the fob causing false presses. There have been plenty of instances where a key fob in a pocket has caused buttons to be pressed, normally resulting in the windows opening

I had it once when I got off a flight and couldn't remember where I'd left my car. Whilst wondering around the car parks, I pressed the fob enough times to lose sync so had to do the relearn via the drivers door lock...

Thanks, Very possible. Managed to avoid the open windows mystery although the open bootlid poltergeist was common when I first got the car. Maybe trouser fashion has chnaged over the last 8 years-or too many pies!

Just praying it's not some module sowmwhere playing up.