Fuel Pressure Adapter (M56 Engine)
Vehicles with the M56 engine, designated Super Low Emission Vehicles (SULEV), have no test port on the fuel rail to which diagnostic equipment may be connected to determine fuel pressure. This was done for emission purposes in an effort to eliminate any points where fuel or fuel vapors could escape. Unfortunately, this limits diagnostic capability should a vehicle have fuel system problems.
BMW tool part # 81 11 0 394 963 has since been discontinued and replaced with AGA Tools part # AGA SFPTA-14.