Fuel Rail Pressure Sensor

Direct injection and diesel systems use it. It controls the high-pressure pump. Faults cause limp mode. Live data comparing target and actual rail pressure helps tell a sensor fault from a pump or regulator fault. Always wait for pressure to drop before opening any fuel line. On some engines the sensor is supplied only with the rail.

A diaphragm converts pressure into voltage.

Fuel under high pressure is dangerous. Some are not sold separately.