The inlet pressure sensor is arranged in the fuel filter housing behind the filter element. This is a BMW-specific component.
It has the task of recording inlet pressure to the high pressure pump (HPP) in the fuel line.
This enables the DDE to reduce the fuel injection quantity at excessively low inlet pressures to the point where engine speed and rail pressure are reduced accordingly. The volume required inlet by the high pressure pump is reduced. This makes it possible for the inlet pressure to the HPP to rise back to the required level.
At an inlet pressure of < 1.5 bar, HPP damage is possible as a consequence of inadequate fill.
The engine can stall suddenly if a differential pressure of ≤ 0.5 bar develops between the inlet and the return lines (pump protection).
