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Cummins ISX12 CM2250 (2010-12) Fault Code: 559 (X) PID: 157 SPN: 157 FMI: 18 Injector Metering Rail 1 Pressure- Data Valid But Below Normal Operating Range- Moderately Severe Level

Circuit Description
The pressure control loop relies on fuel pressure supplied to the high-pressure pump by the fuel gear pump. The ECM monitors rail fuel pressure and engine operating conditions, and changes the flow command to maintain the proper rail fuel pressure. Changes to the flow command result in opening (or closing) of the fuel pump actuator to supply more (or less) fuel to the high-pressure pump.

Component Location
The high-pressure fuel pump is mounted to the gear housing on the intake side of the engine.

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

Conditions for Setting the Fault Codes
The ECM has detected the measured fuel rail pressure is below the commanded fuel rail pressure by at least 250 bar [3625 psi] for 7 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.
Active and stationary regeneration of the diesel particulate filter will be disabled.
The exhaust gas recirculation (EGR) valve will be closed.
Engine torque will be reduced if the engine is operated for an extended period of time with this fault code active.
Conditions for Clearing the Fault Code
To validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop-and-go city driving and steady state highway driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.
To validate the repair using a Chassis Dynamometer Test, utilize a routine that incorporates acceleration and motoring events, steady state highway operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.
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 after the diagnostic runs and passes.
For On-Board Diagnostics (OBD) engines, the ECM will turn OFF the 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 fault codes, as well as extinguish the MIL for OBD applications.

Shop Talk
Before servicing any fuel system components, (such as fuel lines, fuel pump, injectors, etc.) which will expose the fuel system or internal engine components to potential contaminants prior to disassembly, clean the fittings, mounting hardware, and the area around the component to be removed. Dirt or contaminants can be introduced into the fuel system and engine if the surrounding areas are not cleaned, resulting in damage to the fuel system and engine. Use the following procedure in the ISX15 CM2250 Service Manual, Bulletin 4022250. Refer to Procedure 000-009 in Section 0.

If Fault Code 559 is inactive and there are no existing performance complaints, it is possible the vehicle was run out of fuel or the fault code became active if the engine was not primed following fuel filter replacement. Clear the inactive fault code.

Fault Code 559 sets when the engine is operating and measured rail fuel pressure remains at least 250 bar [3625 psi] less than commanded pressure. Once detected, Fault Code 559 will remain active until the engine is turned OFF or until the measured rail fuel pressure matches the commanded rail fuel pressure. When a condition exists that causes Fault Code 559 to become active, it is typical for the fault code to become active when the engine is heavily loaded, and to become inactive when the engine is lightly loaded.

When Fault Code 559 occurs, the fuel system has lost its ability to maintain rail fuel pressure.

Possible causes of this fault code include:

Fuel inlet restrictions (filters, low pressure fuel lines, priming check valve, original equipment manufacturer (OEM) plumbing, etc.)
Fuel gear pump output low
Fuel gear pump pressure regulator stuck open (this can result in hard start and/or no-start complaints)
High-pressure pump capacity decay (high leakage to drain from the high-pressure pump)
Fuel rail pressure relief valve leaks to drain
Fuel rail pressure relief valve opens (at too low a pressure), Fault Code 3727 detects this condition
Injector fuel circuit leaks to drain (injector body, high-pressure connectors, etc.)
Air in the fuel or suction leaks at gear pump shaft seal (can result in hard start/no-start complaints)
Fuel level is below the suction line in the fuel tank
Restricted fuel screen, located in the banjo bolt, at the high-pressure fuel pump inlet, if equipped
External fuel leaks
Air in the fuel will cause starting problems. Use the following procedure in the ISX15 CM2250 Service Manual, Bulletin 4022250. Refer to Procedure 006-003 in Section 6. Use the following procedure in the ISX12/ISX11.9 CM2250 Service Manual, Bulletin 2883445. Refer to Procedure 006-003 in Section 6.

The fuel rail pressure sensor can 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 running. Once the engine is keyed OFF, there can be a significant amount of time waiting for the fuel to depressurize to zero. It is necessary to manually relieve the pressure from the high-pressure fuel rail by loosening the pump to rail line at the rail. At key ON, the fuel rail pressure sensor must read 0 ? 43 bar [624 psi].

Intermittent ECM power supply and ECM ground connections can cause Fault Code 559. If the engine is operating with an active Fault Code 559 and Fault Code 449, 1911, or 2311 is not present, check the ECM power supply for intermittent connections. Fault Code 1117 can also be active if this fault condition exists.

Troubleshooting inactive Fault Code 559 can be difficult. For engines with high counts of Fault Code 559, or if the troubleshooting tree has been exhausted, operate the engine on a chassis dynamometer or conduct a diagnostic road test to duplicate the fault code. Make sure to have a fuel pressure gauge installed at the pressure filter outlet side during the test.

Possible Cause:
1) Fuel pressure relief valve failure
2) High-pressure fuel pump head failure
3) ECM calibration
4) Fuel Tank