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Home >> BMW >> 2012 >> 335xi Automatic Trans >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Engine Performance - Functional Description - E92 >> Engine Performance - Functional Description >> High-Pressure Fuel System >> Rail with rail-pressure sensor
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Rail with rail-pressure sensor

In the rail, the fuel is stored temporarily, then distributed to the injectors.

The rail-pressure sensor measures the current fuel delivery pressure in the rail.

Fig 1: Identifying Rail-Pressure Sensor
G09871870Courtesy of BMW OF NORTH AMERICA, INC.
Index Explanation
1 Electrical connection
2 Evaluating circuit
3 Diaphragm with sensor electronic circuitry
4 High-pressure connection

The high-pressure connection allows the pressurized fuel to reach the diaphragm with its electronic sensor circuitry. The electronic sensor circuitry converts the changes in the diaphragm's shape into an electrical signal. The evaluating circuit processes the signal and forwards an analogue voltage signal to the DME. The voltage signal rises in linear form with increasing fuel delivery pressure.

The signal from the rail-pressure sensor is an important input signal of the DME for activation of the volume control valve (component of the high-pressure pump). If the rail-pressure sensor fails, the volume control valve is activated in emergency operation by the DME.