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Troubleshooting
C4.4 and C7.1 Engines
Media Number -UENR0629-37 Publication Date -01/09/2015 Date Updated -15/06/2020
i08132138
Fuel Rail Pressure Problem
SMCS - 1252-035; 127A-035
Use this procedure to troubleshoot abnormal fuel rail pressure or use this procedure if any of the
following diagnostic trouble codes are active. Refer to Troubleshooting, "Diagnostic Trouble Codes"
for information about the codes.
Table 1
Diagnostic Trouble Codes
J1939 Code Description
CDL
Code (code descriptions may Comments
Code
vary)
No other 157 (1797) codes are active.
262 (3509) codes are not active.
No codes for the high-pressure fuel pump or
High Fuel Rail Pressure : the injectors are active.
157-16 E396-2
Level 2 The fuel rail pressure is above an acceptable
level.
The code is logged.
Engine power is derated.
No other 157 (1797) codes are active.
262 (3509) codes are not active.
No codes for the high-pressure fuel pump or
Low Fuel Rail Pressure : the injectors are active.
157-18 E398-2
Level 2 The fuel rail pressure is below an acceptable
level.
The code is logged.
Engine power is derated.
Service Information System Page 2 of 4
Probable Causes
• Diagnostic codes
• Electrical connectors
• Fuel filters
• Fuel rail pressure sensor
• High-Pressure fuel pump calibration
• Fuel system
• High-pressure fuel pump suction control valve
Recommended Actions
Table 2
Troubleshooting Test Steps Values Results
Result: One of the diagnostic codes listed
1. Diagnostic Codes
in Table 1 is active or recently logged.
A. Connect the electronic service tool
Proceed to Test Step 2.
to the diagnostic connector. Refer to
Diagnostic
Troubleshooting, "Electronic Service
codes Result: A code other than listed in Table 1
Tools", if necessary.
is present.
B. Determine if a diagnostic is active
Repair: Troubleshoot the code. Refer to
or recently logged.
the applicable troubleshooting procedure.
Result: There are suspect connectors.
2. Electrical Connectors Repair: Use the electronic service tool to
perform the "Wiggle Test".
A. Check for the correct installation of
the ECM J1/P1 and the J2/P2 Connectors Repair or replace connectors that are
connectors. Check for correct suspect.
installation of the connector on the
fuel rail pressure sensor. Result: There are no suspect connectors.
Proceed to Test Step 3.
Service Information System Page 3 of 4
3. Fuel Filters Fuel filters Result: The filters have been replaced and
the fault is eliminated.
A. Replace the primary fuel filter and
the secondary fuel filters. Refer to the Return the unit to service.
Operation and Maintenance Manual
for further information. Result: The filters have been replaced and
the fault is still present.
Proceed to Test Step 3.
Result: The "Fuel Rail Pressure
(absolute)" is more than 5,000 kPa
(725 psi).
Repair: Test the fuel rail pressure sensor.
Refer to Troubleshooting, "Sensor Signal
(analog, Active) - Test".
Use the electronic service tool to perform
the "Fuel Rail Pressure Test". If the test
4. Fuel Rail Pressure Sensor
fails, replace the fuel rail. Refer to
Disassembly and Assembly, "Fuel
A. Make sure that the engine has been Pressure
Manifold (Rail) - Remove and Install".
shut down for at least 10 minutes. Use sensor
the electronic service tool to check the
Confirm that the fault has been eliminated.
status of the "Fuel Rail Pressure"
Result: The "Fuel Rail Pressure
(absolute)" is less than 5,000 kPa
(725 psi).
For a 157-16 (E396 (2)) code, contact the
Dealer Solutions Network (DSN).
For a 157-18 (E398 (2)) code, proceed to
Test Step 5.
5. Fuel System Fuel system Result: A fault was found in the fuel
system.
A. Make sure that the level of fuel in
the fuel tank is sufficient. Repair: Rectify any faults and confirm
that the fault is eliminated.
B. Check the high-pressure fuel
system for leaks. Result: The fuel system is OK.
C. Check for air in the low-pressure
Service Information System Page 4 of 4
fuel system. Refer to Systems Proceed to Test Step 6.
Operation, Testing, and Adjusting,
"Air in Fuel - Test".
Result: The PLV has excessive leakage.
6. Pressure Limiting Valve (PLV)
Repair: Replace the fuel rail. Refer to
Disassembly and Assembly, "Fuel
A. Use the electronic service tool to
Manifold (Rail) - Remove and Install".
perform the "Fuel Rail Pressure Relief Pressure
Valve Test". limiting
Confirm that the fault is eliminated.
valve
Note: This test will identify excessive
Result: The PLV is OK.
leakage through the PLV in the fuel
rail.
Contact the Dealer Solutions Network
(DSN).
Result: The solenoid vale test fails.
7. High-Pressure Fuel Pump Suction
Repair: Replace the high-pressure fuel
Control Valve
pump suction control valve and solenoid
High-
assembly.
Use the electronic service tool to pressure fuel
perform a solenoid test on the fuel pump
Result: The solenoid valve test passes.
injection pump. Refer to
Troubleshooting, Solenoid Valve -
Contact the Dealer Solutions Network
Test.
(DSN).
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