This post is from 5 years ago, but I'm seeing this issue now on my 2008 and there's no resolution listed. To further describe the issue:

- car is off/locked, keys in pocket and first approaching only the trunk, pressing the trunk release on trunk won't open it - no response whatsoever - even if I reach the key closer to the front of the car (via the side).

- unlock car first with remote or door handle touch, pressing the trunk release on trunk will open it. Indicates a CA antenna issue, but didn't realize the trunk has a separate one. I guess that makes sense since the door handles have sensors and the trunk release doesn't. Anyone know more about this trunk CA antenna? I did check my fob battery.

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'08 X5 3.0si - Alpine White / Saddle Brown interior
Specs: Sport Pkg, Premium Pkg, Tech Pkg, Comfort Access, Aero Kit, Style 433 staggered 20s on Conti DWS
Mods: Carbon 35 tint, LED angel eyes, GP Thunder 7500k fogs, H&R 20mm/25mm spacers, clear reflectors, gunsmoke-tinted taillights
Coded: Digital speedo, windows/sunroof/tailgate close via keyfob

X5 pics at Flickr