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This would be carried out by the dealer as part of the annual service.

The battery can be changed but the key has to be reprogrammed to the alarm system.

The car charges the key when you drive. You can recode the key to the car... im not aure about newer bmw's, but in mine at the time.... open drivers door, close it, put key in ignition and turn to the 2nd position then remove key again within 5 seconds. hold down the lock button and click the unlock button 3 times, then release. the doors will lock and unlock when you have done it right. to code more keys you have to do the hold and click on the next key right away after the doors have locked and unlocked from the first time.

if your car isnt charging the key, check the fuses first. this has happened to me, blowing the charging fuse... it was an e39 sport and the fuse was in the battery compartment in the boot. not sure where the x5 1 will be tho.

you could give this a try before spending any money.

Don't let anyone tell you that Walmart's Yellow Maxx Batteries are cheap. The Deka parent company (East Penn Battery Company) in Lyon Station PA. builds the three year free replacement Maxx Batteries for $69.00 ea. Depending on physical size they knock out 850-1000 cold cranking amps. I'm susre you've heard of the new Sears "cough" $185.00 battery. It's made by AC-Delco. All but the Sears Gold batteries are made in Mexico by who knows! The warranty on these batteries is terrible. Innerstate is made by Thompson Controls (USA). Thompson Controls also makes Auto Zone's batteries. Auto Zone batteries have a better warranty than do Innerstate's. Knock on wood I have an Innerstate that's going on 8 yrs. old and it still holds a 80% charge.Consumers Reports rates The Yellow Maxx units from Walmart at the top or near the the top in every battery size.

There are 2 kinds of keys. One is bigger and squarish and has a removable rectangular shaped cover at the back which hides 2 small screws holding a bigger cover inside of which lies the battery. This battery can be replaced easily and if done quickly would not require

re-initialization.

The other key is smaller with no removable cover. This one has the capacitor type of battery which can not be replaced. It charges while inserted in the ignition key with the key on. When the battery is bad, then you have to replace the whole key.

But try re-initializing the malfunctioning key first.See my previous postings for details. And have you tried your other keys?

Firstly, I assume you don't have the car's handbook!

Just take it to any shop that does key cutting & watch batteries: They'll supply & fit the battery. It shouldn't need reprogramming.

yea you can change the battery but i would recomend you let the dealership have a look at it and they will do it for you it could also be something else german cars are kinda wierd but there awsome cars cant lie haha

take it to the dealership

as above