12251-ZW5-023 Honda SEE PART DETAILS - PRI; GASKET, CYLINDER HEAD (Honda Code 7360670).

Probable Causes
Diagnostic codes
Parameters in the Electronic Control Module (ECM)
Air intake system or exhaust system
NRS valve
Valve lash
Turbocharger or turbochargers
Low compression (cylinder pressure)
Electronic unit injectors
Individual malfunctioning cylinderRecommended Actions
Note: Complete the procedure in the order in which the steps are listed.
Table 1
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
A. 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.
B. Use the electronic service tool to check for active or logged codes.
Diagnostic codes
Result: A diagnostic code is present.
Repair: Troubleshoot the code.
Result: A diagnostic code is not present.
Proceed to Test Step 2.
2. Parameters in the Electronic Control Module (ECM)
A. Use the electronic service tool to verify that the correct parameters are being used. Refer to Troubleshooting, "Configuration Parameters" for additional information.
Parameters
Result: The parameters are not correct.
Repair: Input the correct parameters. Refer to Troubleshooting, "Configuration Parameters" for additional information.
Result: The parameters are correct.
Proceed to Test Step 3.
3. Air Intake and Exhaust System
A. Observe the check engine lamp. Check for an air filter restriction indicator, if equipped. Replace a plugged air filters. Refer to the Operation and Maintenance Manual.
B. Check the air inlet and exhaust system for restrictions and/or leaks.
Restrictions
Result: There are restrictions in the air inlet or exhaust system.
Repair: Make the necessary repairs, Refer to Systems Operation/Testing and Adjusting, "Air Inlet and Exhaust System - Inspect" for additional information.
Result: There are no restrictions in the air inlet or exhaust system.
Proceed to Test Step 4.
4. NRS Valve
A. Use the electronic service tool to perform the "Air System Motor Valve Verification Test".
Pass
Result: The "Air System Motor Valve Verification Test" failed.
Repair: Troubleshoot active diagnostic codes generated as a result of the test.
Result: The "Air System Motor Valve Verification Test" passed.
Proceed to Test Step 5.
5. Valve Lash
A. Check the valve lash.
Valve lash
Result: The valve lash is incorrect.
Repair: Check the valve lash. Refer to Systems Operation, Testing, and Adjusting, "Engine Valve Lash - Inspect" for the correct procedure.
Result: The valve lash is correct.
For engines with a single turbocharger, proceed to Test Step 6.
For engines with two turbochargers, proceed to Test Step 7.
6. Turbocharger
Note: This Test Step is only applicable to engines with a single turbocharger.
Note: The turbocharger that is installed on the engine is a non-serviceable item. If any mechanical fault exists, then the faulty turbocharger must be replaced.
A. Ensure that the mounting bolts for the turbocharger are tight.
B. Check that the oil drain for the turbocharger is not blocked or restricted.
C. Check that the compressor housing for the turbocharger is free of dirt and debris. Make sure that the housing is not damaged.
D. Check that the turbine housing for the turbocharger is free of dirt and debris. Make sure that the housing is not damaged.
E. Check that the turbine blades rotate freely in the turbocharger.
F. Ensure that the wastegate on the turbocharger is adjusted correctly. Refer to Systems Operation, Testing, and Adjusting, "Turbocharger - Inspect". If the wastegate actuator is faulty, replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
Turbocharger
Result: There is a fault in the turbocharger.
Repair: Repair the turbocharger or replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
Result: The turbocharger is OK.
Proceed to Test Step 8.
7. Turbochargers
Note: This Test Step is only applicable to engines with two turbochargers.
Note: The turbochargers that are installed on the engine are non-serviceable items. If any mechanical fault exists, then the faulty turbocharger must be replaced.
A. Ensure that the mounting bolts for the turbochargers are tight.
B. Check that the oil drains for the turbochargers are not blocked or restricted.
C. Check that the compressor housings for the turbochargers are free of dirt and debris. Make sure that the housings are not damaged.
D. Check that the turbine housings for the turbochargers are free of dirt and debris. Make sure that the housings are not damaged.
E. Check that the turbine blades rotate freely in the turbochargers.
F. Ensure that the wastegate on the high-pressure turbocharger is adjusted correctly. Refer to Systems Operation, Testing, and Adjusting, "Turbocharger - Inspect". If the wastegate actuator is faulty, replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
Turbocharger
Result: There is a fault in one of the turbochargers.
Repair: Repair the turbocharger or replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
Result: The turbochargers are OK.
Proceed to Test Step 8.
8. Low Compression (Cylinder Pressure)
A. Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test".
Cylinder compression
Result: The results of the compression test are outside the specifications.
Repair: Investigate the cause and rectify any faults.
Note: Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Result: The results of the compression test are OK.
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.
Contact with high-pressure fuel may cause personal injury or death. Wait 10 minutes after the engine has stopped to allow fuel pressure to purge before any service or repair is performed on the engine fuel lines.
Table 2
Troubleshooting Test Steps Values Results
9. Electronic Unit Injectors
A. Use the electronic service tool to perform the automatic "Cylinder Cut Out Test".
Note: If the compression test that was performed in Test Step 8 was satisfactory, the "Cylinder Cut Out Test" will identify any faulty injectors.
Electronic Unit Injectors
Result: A faulty injector is indicated.
Repair: Remove any faulty electronic unit injec