My keyfob only has a 2m range which from what I understand is likely to be the diversity antenna (although my radio signal seems ok).

Had a look at it on the weekend and was expecting it to be corroded like others I've seen on here but it looked fine.. Can these still fail without any obvious visual signs?

Just checking out part numbers on real oem and I'm a little confused what frequency I need. Obviously it's probably printed on the unit itself but it's fiddly get to so don't want to needlessly have to take it out again if there's another way to check.

My car is a 55 plate e60 530D m sport auto.

The possible part numbers are here:

RealOEM.com - Online BMW Parts Catalog

Will be one of the first 3 on the list

 

You don't necessarily have to have just bad connectors for the antenna to not work right. Components on the antenna board itself could go bad. I'd suggest replacing it.

I had the very same issue with my keyfob, it would only arm/disarm the car when standing right next to it. My radio meanwhile worked fine. As soon as I replaced my antenna the range greatly improved - I could arm the car (while in my garage) from my bedroom at the opposite end of my home. The best bet to knowing what frequency your antenna is is to remove the old one and match it. Accessing the antenna ain't that bad of a chore. In fact, you may be able to read the frequency on the antenna without having to remove or disconnecting it. Good luck

 

It's the 868mhz version - part number 65206931718 which has now been superseded by 65209193832.

I've called BMW Cotwolds and they can provide this for £265 which seems high. Do you guys have any ideas where else I can check? eBay is turning up nothing currently.