00 00... Fuel lines, hoses and tank(s): visual inspection for routing, condition and leaks
WARNING: This page is about a different car, the 2003 BMW 525i, 2002 BMW 525i, and 2001 BMW 525i. However, it is still accessible from the selected car via links, so may be relevant.
Check fuel lines and hoses and fuel system connections for traces of fluid.
Check fuel tank(s) and hoses for damage such as cracks, flattening etc.
Check that fuel lines are routed correctly.