Cummins X12 CM2350 X119B (2018 & Newer) Fault Code: 484 PID: PID 129 SPN: 1349 FMI: 4 Injector Metering Rail 2 Pressure Sensor Circuit- Voltage Below Normal, or Shorted to Low Source

Circuit Description
The engine control module (ECM) provides a 5 volt supply to the fuel rail pressure sensor using a dedicated sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The fuel rail pressure sensor provides a primary fuel pressure signal to the ECM on the fuel rail pressure sensor signal 1 circuit. The sensor also provides a secondary fuel pressure sensor signal on the fuel rail pressure signal 2 circuit. This sensor signal voltage changes based on the pressure in the fuel rail. The ECM will detect a high signal voltage at high rail pressure conditions. The ECM will detect a low signal voltage during low rail pressure conditions.

Component Location
The high-pressure fuel pump is mounted to the gear housing. The fuel pump actuator is mounted on the fuel pump. The fuel pressure sensor is mounted in the high pressure fuel rail. The fuel pressure relief valve is mounted on the high pressure fuel rail.

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

Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the fuel rail pressure 2 signal voltage was less than 0.25-VDC for more than 3 seconds.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
Exhaust Gas Recirculation (EGR) valve operation will be disabled.
Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
Conditions for Clearing the Fault Code
To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three 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.

Shop Talk
Possible causes of this fault code include:

A malfunctioning fuel rail pressure sensor
A short circuit to ground in the engine harness

Possible Cause:
1) ECM failure
2) Engine harness