BMW E39 5-Series Tail Light Replacement | 1997-2003 525i, 528i, 530i and 540i 

If you see the bulb warning display showing you have bad rear bulb you should check your tail light assemblies.
You can remove the bulb housing and the bulbs to check for poor connections. You can also remove the tail light itself to replace a cracked lens or to check the seal to see if it is the cause of water leaking into your trunk.
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