94002-06490-0S Honda NUT, HEX. (6MM) (Honda Code 1986488).

Probable Causes
Diagnostic codes
ECM parameters
Accessory and/or parasitic loads
Flash file
Throttle signal from the throttle position sensor
Air intake and exhaust system
Turbocharger or turbochargers
Fuel supply
Transfer Pump Inlet Regulator (TPIR)
Electric Fuel Lift Pump (EFLP)
Return fuel lines
Low compression (cylinder pressure)
Electronic unit injectors
Individual malfunctioning cylinders
Table 1
Associated Diagnostic Trouble Codes
J1939 Code CDL Code
157-18 E398 (2) Recommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 2
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
A. Establish communication between the electronic service tool and the Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Download the Warranty Report and the Product Status Report with Histograms before performing any troubleshooting or clearing any diagnostic codes.
Note: The downloaded information will be required by the Dealer Solutions Network (DSN) if troubleshooting assistance is needed.
C. Use the electronic service tool to check for active or logged codes.
Diagnostic codes
Result: There are active or logged codes.
Repair: Troubleshoot any codes before continuing with this procedure.
Result: There are no active or logged codes.
Proceed to Test Step 2.
2. ECM Parameters
A. Use the electronic service tool to verify that the correct engine parameters are being used. Refer to Troubleshooting, "Configuration Parameters" for additional information.
B. If applicable, verify that all parameters for any parasitic loads are correct.
Parameters
Result: The parameters are not configured correctly.
Repair: Correctly configure the parameters.
Verify that the configuration change eliminated the fault.
Result: The parameters are configured correctly.
Proceed to Test Step 3.
3. Accessory and/or Parasitic Loads
A. Check all accessory equipment for problems that may create excessive load on the engine.
B. Check for any excess parasitic load on the engine.
Parasitic loads
Result: There is an excessive load on the engine.
Repair: Diagnose and repair the fault.
Verify that the repair eliminated the fault.
Result: There is not an excessive load on the engine.
Proceed to Test Step 4.
4. Flash File
A. Verify that the latest flash file is installed in the Electronic Control Module (ECM). Refer to Troubleshooting, "ECM Software - Install" for the correct procedure.
Flash file
Result: The latest flash file is not installed in the ECM.
Repair: Install the latest flash file. Verify that the repair eliminated the fault.
Result: The latest flash file is installed in the ECM.
Proceed to Test Step 5.
5. Throttle Signal for the Throttle Position Sensor
A. Use the electronic service tool and observe the signal for the throttle position sensor. Make sure that the throttle reaches the 100% raw position and the calibrated position.
CAN data link
Result: The throttle signal is erratic or does not reach the 100% raw position or the calibrated position.
Repair: Refer to Troubleshooting, "Speed Control (Analog) - Test" or refer to Troubleshooting, "Speed Control (PWM) - Test". If the engine has a multi-position Throttle switch, refer to Troubleshooting, "Switch Circuits - Test".
Result: The throttle signal is OK.
Proceed to Test Step 6.
6. Air Intake and Exhaust System
A. Check the air filter restriction indicator, if equipped.
B. Check the air inlet and exhaust system for restrictions and/or leaks.
Restrictions
Result: The air filter is plugged.
Repair: Clean or replace the air filter. Refer to the Operation and Maintenance Manual for further information.
Result: There are restrictions in the air inlet or exhaust system.
Repair: Make the necessary repairs, Verify that the repair eliminated the fault.
Result: There are no restrictions in the air inlet or exhaust system.
For engines with a single turbocharger, proceed to Test Step 7.
For engines with a two turbochargers, proceed to Test Step 8.
7. Turbocharger
A. Check for the correct operation of the turbocharger.
Turbocharger
Result: The turbocharger is not operating correctly.
Repair: Repair or replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
If a turbocharger equipped with an electronic wastegate is replaced, use the electronic service tool to perform the "Turbocharger Wastegate Actuator Replacement Reset".
Use the electronic service tool to perform the "Air System Motor Valve Verification Test"
Result: The turbocharger is operating correctly.
Proceed to Test Step 9.
8. Turbochargers
A. Check for correct operation of the turbochargers.
Turbochargers
Result: The turbochargers are not operating correctly.
Repair: Repair or replace the faulty turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
If a turbocharger equipped with an electronic wastegate is replaced, use the electronic service tool to perform the "Turbocharger Wastegate Actuator Replacement Reset".
Use the electronic service tool to perform the "Air System Motor Valve Verification Test"
Result: The turbochargers are operating correctly.
Proceed to Test Step 9.
Contact with high pressure fuel may cause fluid penetration and burn hazards. High pressure fuel spray may cause a fire hazard. Failure to follow these inspection, maintenance and service instructions may cause personal injury or death.
Ensure that the pressure in the high-pressure fuel system has been purged before any service or repair is performed on the high-pressure fuel system.
Refer to Operation and Maintenance Manual, High-Pressure Fuel Lines for the time taken for the high-pressure fuel system to be purged.
Table 3
Troubleshooting Test Steps Values Results
9. Fuel Supply
A. Check for leaks from the high-pressure fuel lines.
B. Ensure that the vent in the fuel cap is not filled with debris.
C. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
D. If the temperature is below 0 °C (32 °F), check for solidified fuel (wax).
E. Check the primary filter/water separator for water in the fuel.
F. Check for fuel supply lines that are restricted.
G. Replace the in-line fuel filter that is installed upstream of the Electric Fuel Lift Pump (EFLP) (C7.1 engines only).
H. Replace the primary and secondary fuel filters.
I. Check the diesel fuel for contamination. Refer to Systems Operation, Testing, and Adjusting, "Fuel Quality - Test".