Cummins ISB4.5 CM2150 Fault Code: 449 PID: SPN: 157 FMI: 0 Injector Metering Rail 1 Pressure – Data Valid but Above Normal Operating Range – Most Severe Level.

Circuit Description
The electronic control module (ECM) monitors engine-operating conditions, including the reading of fuel rail pressure, and changes the flow command to either increase (OPEN the fuel pump actuator) or decrease (CLOSE the fuel pump actuator) the fuel supply to the high-pressure pump.

Component Location
The high-pressure relief valve is located on the fuel rail. The fuel pump actuator is located on the engine-mounted fuel pump

Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes
The ECM has detected that the measured fuel rail pressure has been above the maximum pressure allowed by the fuel pressure relief valve.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE light and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails. Power derate can occur on some engines.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute. The fault code will go inactive once the fuel rail pressure returns to normal operatiing levels.
-The ECM will turn off the amber CHECK ENGINE light immediately after diagnostic runs and passes.
-The ECM will turn off the MIL after three consecutive ignition cycles that the diagnostic runs and passes.
-This fault code and the MIL can also be cleared with INSITE™ electronic service tool.

Shop Talk
Fault Code 449 is not used to indicate a fuel pressure relief valve opening. It is used to indicate a fuel pressure relief valve that fails to open or does not regulate pressure. Troubleshooting must be focused on inspecting the drain line path of the fuel pressure relief valve for restrictions/obstructions and checking or replacing the fuel pressure relief valve. A restriction in the fuel-drain-to-tank return line can prevent unneeded fuel from exiting the fuel system. Check the fuel drain line restriction from the fuel rail to the tank for damage.