they stop working because water leaks in and corodes the connections. you can simply change the cluster or take your old one apart an clean up the connection and terminals.

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2007 X5 4.8i - Sapphire Black
Specs: Aero kit/Pan roof/20" Y Spoke/HUD/Active seats/Heated seats/Comfort seats/Vent perf seats/Bi Xenons/ Navigation/Bluetooth/
Mods: OEM LED number plate lights/ Pheonix Gold Subwoofer/ Solar Guard Window film/Digital TV/ I Pod Kit