Why is it always the simple jobs?! The following happened; 

Change remote key battery appeared on dash

Changed battery

 Tried key from inside house, press open, lights flash, mirrors go out, doors appear open!

 Press close, lights flash, mirrors don’t move

 Go out to car. It’s locked! Doors are locked and won’t open. Key appears dead. Nothing happens.

 Use spare key and doors open!

 Do I need to do some sort of sequence to activate key with new battery?! Am sure I changed battery before and didn’t have issue or might be different car, I can’t quite remember. Any advice appreciated. Thanks!

    

I have changed mine before with no issues but maybe there is another link/sync issue...

 

How long was the battery out of the key?

I've changed the batteries on both of my keys several times & haven't had any problems once the new battery is added.

as above, I'm not sure if there is some sort of time limit for removing the battery but I wouldnt say I did it particularly fast although I did have the new battery at hand to insert immediately once the old one was out.

Edited 3 July, 20196 yr by Gabbo

19 hours ago, Martskoda said:

 Key appears dead. Nothing happens.

 Use spare key and doors open!

Perhaps I'm being over simplistic but the new battery sounds like it's a dud. Try another.

23 minutes ago, Scot5 said:

Perhaps I'm being over simplistic but the new battery sounds like it's a dud. Try another.

...... would appear to be the correct answer! I actually tried two different batteries though but they were bought at the same time. Hopefully that has sorted it but am carrying spare key just in case!

I had a similar experience: after changing the keyfob battery from a duracell DL2025 to a maxell CR2025 the keyfob would not work any more. When I pressed a button, the little red light on the fob would not blink. The car would not react to key presses with the fob. Then I put the Duracell back in but no luck. The Duracell measured 3.0 V, the Maxell 3.3 V. After reading up on this issue I swapped the battery to a Maxell CR2032. This is a bit thicker but said to have more power. It will still fit in the keyfob. Now the key is functional again: the LED blinks when pressing buttons, car unlocks / locks. I did't need to reactivate the key. Hope this helps.