High-pressure control
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2017 BMW X3, 2016 BMW X3, 2015 BMW X3, 2014 BMW X3, and 2013 BMW X3. However, it is still accessible from the selected car via links, so may be relevant.
The quantity-control valve regulates fuel delivery between the low-pressure and high-pressure sides of the high-pressure pump. The desired rail pressure is set by the 3 control types. The signal from the rail pressure sensor serves as an input signal for the digital engine electronics (DME) to activate the quantity control valve.
If the rail pressure sensor or high pressure pump fails, the quantity control valve is not longer activated by the Digital Engine Electronics (DME). An integrated bypass valve in the high pressure pump allows continued but restricted driving.