Yesterday I had a dashboard warning for 'Replace battery in remote key'. Today I tried with Mrs S's key and got the same message. Is this a time related message - the car is now 6 years old? - Or is it generated by low voltage in the key itself? Seems strange that they both give the warning seeing as Mrs S's key is used much less than mine. New batteries are available on eBay for around £3.99 for a pair - or should I just let the local dealership replace them at the next service? I'm going to be booking it in for a service (oil-change, oil-filter, fuel-filter, air-filter, cabin filter) in the next few weeks anyway. Is a battery change included in the BMW 'Vehicle Check' ? I suspect they would charge me a lot more that changing the batteries myself.