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Injector Metering Rail Number 1 Pressure – Data Valid But Above Normal Operating Range – Most Severe Level
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Overview
| CODE | REASON | EFFECT |
| Fault Code: 449 PID: P94 SPN: 157 FMI: 0 LAMP: Amber SRT: |
Injector Metering Rail Number 1 Pressure – Data Valid But Above Normal Operating Range – Most Severe Level. The ECM has detected that fuel pressure in the fuel rail is higher than the fuel pressure relief valve. |
None or possible engine noise associated with higher injection pressures (especially at idle or light load) or possible power derate. |
 Fuel System
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Circuit Description
The electronic control module (ECM) monitors engine-operating conditions, including the reading of rail fuel pressure, and changes the flow command to either increase (OPEN the electric fuel control valve) or decrease (CLOSE the electric fuel control valve) the fuel supply to the high-pressure pump.
Component Location
The high-pressure relief valve is located on the fuel rail. Refer to Procedure 100-002 in Section E.
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 is 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 immediately when the diagnostic runs and fails. Power derate can occur on some engines.
Conditions for Clearing the Fault Code
The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.
Shop Talk
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM. Refer to Procedure 019-032 (ECM Calibration Code) in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.
Fault Code 449 is activated when the sensed rail fuel pressure exceeds for several consecutive seconds the opening pressure of the fuel pressure relief valve.
Fault Code 449 is not used to indicate a fuel pressure relief valve opening. It is used to indicate a fuel pressure relief valve which 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-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.
The fuel rail pressure sensor must also be checked. When checking the fuel rail pressure sensor accuracy, make sure the high-pressure fuel rail is not pressurized. The fuel pump, high-pressure fuel lines, and fuel rail contain very high-pressure fuel. Do not loosen any fittings while the engine is operating. Once the engine is keyed off, there could be a significant amount of time waiting on the rail to depressurize to 0. It is necessary to manually relieve the pressure from the high-pressure fuel rail by loosening the pump to rail line at the rail.
Refer to Troubleshooting Fault Code t05-449
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