Cummins ISB4.5 CM2150 Fault Code: 452 PID: SPN: 157 FMI: 4 Injector Metering Rail 1 Pressure Sensor Circuit – Voltage Below Normal or Shorted to Low Source.

Circuit Description
The fuel delivery pressure sensor responds to pressure changes in the fuel rail. The fuel delivery pressure sensor has a 5 volt supply circuit, a sensor signal voltage, and a return circuit. The electronic control module (ECM) provides a 5 volt supply to the fuel rail pressure sensor using a common sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The fuel rail pressure sensor provides a signal to the ECM on the fuel rail pressure sensor signal circuit. This sensor signal voltage changes based on the pressure in the fuel rail. The ECM will detect a low signal voltage at high rail pressures. The ECM will detect a high signal voltage during low rail pressure conditions.

Component Location
The fuel pressure sensor is installed in the fuel rail.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes
The ECM detects that the fuel rail pressure signal voltage is less than a calibratible value for more than 1 second. This can be caused by a short circuit to ground on the 5-VDC supply or signal wire.

This fault will also become active if a device that is powered by the common 5 volt power supply is shorted to ground.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately after the diagnostic runs and fails.
-Engine torque can possibly be reduced.
-A default value for the fuel rail pressure reading is used.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.

For engines equipped with an airless SCR aftertreatment system:
-This fault code can not be cleared with INSITE™ electronic service tool.
-The ECM will turn off the amber CHECK ENGINE lamp and/or MIL immediately after the diagnostic runs and passes.
-Use INSITE™ electronic service tool to verify the fault code is inactive.
-The inactive fault code will be cleared from the memory after 9600 hours of engine operation without a reoccurrence.

For all other engines:
-The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
-For On-Board Diagnostics (OBD) engines, the ECM will turn off the MIL after 3 consecutive trips where the diagnostic runs and passes.
-The “Reset All Faults” command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Possible Causes
-Engine harness; the supply or signal wire is shorted to ground
-Other components; any component connected to the common power supply is shorted to ground
-Malfunctioning sensor
-Malfunctioning ECM.