The N54 engine comes equipped with a high precision injection (HPI) system where fuel injectors are of a piezo-electric type; voltage from ECM controls the opening of the injector vale through activation of the piezo element. The ECM controls the time for which the injectors are open in ms in order to regulate the air/fuel mixture, while the injectors pop out to the side, a highly refined cone shape in this case. Working at high system pressures of up to 200 bar in the case of HPI system, an added efficiency is realized. While manufacturing, tolerances for injector amount of adjustment are identified by a six digit number mixture important for fuel injector adaptation. Further, the injection performance data of injector voltage for control is stored in the ECM for each of the piezo actuator with respect to metering and switch in order to respond to the voltage requirement during the running of the engine. An adjustment is required when replacing an injector, and the adjustment is done with a BMW factory scan tool or an equivalent. If a fault occurs in the system, such as High Pressure Sensor failure, the fuel supply control valve will be turned off and fuel will vent into the rail. Limp-home mode can be precipitated by problems such as implausible high pressure sensor values, faulty fuel supply control valve, suspected or actual leakage in high pressure system, failure of high pressure pump, or failure of high pressure sensor.