Diagnostic Test
- LOW FUEL
- VEHICLE CONFIGURATION
Is the vehicle a pickup equipped with a 68RFE automatic transmission?
Yes
- Vehicle is equipped with a 68RFE automatic transmission - Go To 12
No
- Vehicle is equipped with a G56 Manual or AISIN automatic transmission - Go To 3
- CHECK FOR OTHER DTCS
- Read the Freeze frame data.
Is the DTC equal to the freeze frame DTC?
Yes
- Go To 4
No
- Repair any other DTCs first.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Read the Freeze frame data.
- CHECK FOR DAMAGED FUEL LINES
- Visually inspect the injector supply lines for damage.
Do you have any kinked or bent fuel lines?
Yes
- Replace damaged fuel lines.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 5
- Visually inspect the injector supply lines for damage.
- CHECK THE VALVE TRAIN
- Visually inspect the valve train and check the valve lash on the suspect cylinders.
Is the valve train functional and the lash within the specifications listed in the service manual?
Yes
- Go To 6
No
- Adjust the lash or fix or repair any damaged components.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Visually inspect the valve train and check the valve lash on the suspect cylinders.
- CHECK FOR OBSTRUCTED FUEL INJECTOR SUPPLY
- Remove the fuel injector supply lines for the suspect cylinders.
- Inspect both ends of the fuel injector supply lines for damage.
- Using shop air pressure, blow out the fuel injector supply lines to verify that they are not obstructed.
Are the fuel lines free of debris or damage?
Yes
- Go To 7
No
- Replace the damaged or obstructed fuel injector supply lines.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK FOR DAMAGED OR OBSTRUCTED HIGH PRESSURE CONNECTORS
- Remove the high pressure connectors for the suspect cylinders.
- Inspect both ends of the high pressure connectors for signs of damage.
- Using shop air pressure, blow out the high pressure connectors to verify that they are not obstructed.
Are the high pressure connectors free of debris or damage?
Yes
- Go To 8
No
- Replace the damaged or obstructed high pressure connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK THE FUEL INJECTOR AND VALVE COVER HARNESS TERMINALS
- Turn the ignition off.
- Visually check the valve cover connectors, wiring, and fuel injector terminals for loose connections or damaged threads.NOTE:
The valve cover gasket terminal nut to injector terminal torque should be 1.5 Nm (13 in-lbs).
Are the connections, wiring, and terminals good?
Yes
- Go To 9
No
- Repair the connections as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- INTERNAL DAMAGED FUEL INJECTOR
- With the scan tool, erase DTCs.
- Switch the misfiring injectors and high pressure connectors with injectors and high pressure connectors from cylinders that are firing properly.
- Idle the vehicle for a minimum of 2 minutes. If the coolant temperature is below 60°C (140° F), allow the engine to idle until the coolant temperature is above 60°C (140° F). The misfire monitor will not run if the coolant temperature is below 60°C (140° F).
Did the misfire DTC follow the suspect injectors and high pressure connectors?
Yes
- Replace the internal damaged fuel injector and high pressure connector.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 10
- CHECK FOR INTERNAL ENGINE DAMAGE
- Perform engine compression test.
Did the suspect cylinders pass the compression test?
Yes
- Go To 11
No
- Repair the internal damage to the engine.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Perform engine compression test.
- CHECK FOR INTERNAL ENGINE DAMAGE
- Perform engine leak down test.
Did the suspect cylinders pass the leak down test?
Yes
- Test Complete.
No
- Repair the internal damage to the engine.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Perform engine leak down test.
- CHECK FOR OTHER DTCS (FOR VEHICLES EQUIPPED WITH 68RFE TRANSMISSIONS)
- Ignition on, engine not running.
- Using the scan tool, read DTCs.NOTE:
If P020A, P020B, P020C, P020D, P020E, or P020F are present, perform the Diagnostics for that DTC before continuing with this one.
Are there any DTCs present for the EGR Valve, EGR Airflow Control Valve, Turbo, or the Exhaust Manifold Pressure (EMP) Sensor?
Yes
- Repair any other DTCs first.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 13
- CHECK THE EMP SENSOR, SENSOR TUBE, AND PRESSURE SENSING PORTS FOR DEBRIS
- Remove the EMP Sensor from the pressure sensing port.
- Remove the EMP Sensor tube from the exhaust manifold.
- Inspect both the EMP Sensor and the sensor tube for debris. Also inspect the threaded port where the EMP sensor tube attaches to the exhaust manifold for debris.
Were the EMP Sensor, EMP Sensor Tube, and the threaded sensor tube port in the exhaust manifold free of debris?
Yes
- Go To 15
No
- Remove the debris.
- Go To 14
- CHECK FOR MISFIRE
- Ignition on, engine not running.
- Using the scan tool, record and save the Freeze Frame data.
- Use the Freeze Frame report to determine the operating conditions under which the misfire DTC set. Pay particular attention to vehicle speed, engine speed, and throttle position.
- Using the scan tool, erase all DTCs.
- Turn the ignition off for 75 seconds.
- Operate the vehicle in the conditions determined from the Freeze Frame in sub-step 2. If Freeze Frame is unavailable, operate the vehicle in a variety of conditions - idle, steady state, and light to moderate throttle acceleration. Operate the vehicle for at least 10 minutes.
- Turn the ignition off for 75 seconds.
- Ignition on, engine not running.
- Using the scan tool, read DTCs.
Did any misfire DTCs return as pending or active?
Yes
- If any single cylinder misfire DTC set (P0301, P0302, P0303, P0304, P0305, P0306), perform the appropriate diagnostic tree for the cylinder(s) that set the DTCs.
- If P0300 set by itself, Go To 15
No
- Test complete.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- PERFORM THE FUEL SYSTEM RUN UP TEST
- With the scan tool, navigate to System Tests and perform the Fuel System Run Up Test.NOTE:
This test will take approximately 350 seconds to complete. The PCM will cut out each individual Fuel Injector three times and calculate the delta RPM change. Based on the delta RPM change, the test will indicate a bad cylinder based on the limits that have been set. When the test is complete, the engine will return to idle.
NOTE:DTC P2201 will set while this test is running and can be disregarded. After the test has finished, this code can be cleared and should not be diagnosed.
Do the results indicate that a cylinder is out of spec?
Yes
- Go To 16
No
- Go To 23
- With the scan tool, navigate to System Tests and perform the Fuel System Run Up Test.
- CHECK FOR DAMAGED FUEL LINES
- Visually inspect the injector supply lines (for the cylinder that failed the Fuel System Run Up test) for damage.
Do you have any kinked or bent fuel lines?
Yes
- Replace damaged fuel lines.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 17
- Visually inspect the injector supply lines (for the cylinder that failed the Fuel System Run Up test) for damage.
- CHECK THE VALVE TRAIN
- Visually inspect the valve train and check the valve lash on the suspect cylinders.
Is the valve train functional and the lash within the specifications listed in the service manual?
Yes
- Go To 18
No
- Adjust the lash or fix or repair any damaged components.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Visually inspect the valve train and check the valve lash on the suspect cylinders.
- CHECK FOR OBSTRUCTED FUEL INJECTOR SUPPLY
- Remove the fuel injector supply lines for the suspect cylinders.
- Inspect both ends of the fuel injector supply lines for damage.
- Using shop air pressure, blow out the fuel injector supply lines to verify that they are not obstructed.
Are the fuel lines free of debris or damage?
Yes
- Go To 19
No
- Replace the damaged or obstructed fuel injector supply lines.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK FOR DAMAGED OR OBSTRUCTED HIGH PRESSURE CONNECTORS
- Remove the high pressure connectors for the suspect cylinders.
- Inspect both ends of the high pressure connectors for signs of damage.
- Using shop air pressure, blow out the high pressure connectors to verify that they are not obstructed.
Are the high pressure connectors free of debris or damage?
Yes
- Go To 20
No
- Replace the damaged or obstructed high pressure connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK THE FUEL INJECTOR AND VALVE COVER HARNESS TERMINALS
- Turn the ignition off.
- Visually check the valve cover connectors, wiring, and fuel injector terminals for loose connections or damaged threads.NOTE:
The valve cover gasket terminal nut to injector terminal torque should be 1.5 Nm (13 in-lbs).
Are the connections, wiring, and terminals good?
Yes
- Go To 21
No
- Repair the connections as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK FOR INTERNAL ENGINE DAMAGE
- Perform engine compression test.
Did the suspect cylinders pass the compression test?
Yes
- Go To 22
No
- Repair the internal damage to the engine.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Perform engine compression test.
- CHECK FOR INTERNAL ENGINE DAMAGE
- Perform engine leak down test.
Did the suspect cylinders pass the leak down test?
Yes
- Replace the fuel injector(s) and high pressure connector(s) for the suspect cylinders.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Repair the internal damage to the engine.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Perform engine leak down test.
- CHECKING FUEL QUALITY/CONTAMINATION
- Check the quality of the fuel using the DIESEL FUEL CONTAMINATION TEST PROCEDURE. Refer to DIESEL FUEL CONTAMINATION TESTING PROCEDURE
.
Was any contamination detected?
Yes
- Perform the appropriate repair according to the testing and cleaning procedure.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 24
- Check the quality of the fuel using the DIESEL FUEL CONTAMINATION TEST PROCEDURE. Refer to DIESEL FUEL CONTAMINATION TESTING PROCEDURE
.
- INJECTOR RETURN FLOW TEST
- Perform the Injector Return Flow test. Refer to DIAGNOSIS AND TESTING, 6.7L
.
Does the injector drainage meet the test specification?
Yes
- Go To 25
No
- Repair the cause of high Fuel Injector leakage.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Perform the Injector Return Flow test. Refer to DIAGNOSIS AND TESTING, 6.7L
.
- CHECK THE ENGINE PRESSURE SENSORS
- Turn the engine off, ignition on.
- Using the scan tool, compare the Barometric Pressure Sensor and the Exhaust Pressure Sensor reading.
Are the two readings equal?
Yes
- Go To 26
No
- Compare the two readings to the Inlet Air Pressure Sensor reading. Replace the sensor that does not match the Inlet Air Pressure Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- CHECK CRANKCASE FILTER
- Verify proper Crankcase Filter operation.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 27
- Verify proper Crankcase Filter operation.
- CHECKING THE INTAKE SYSTEM
- Check for inlet restriction, inspect air filter for excessive dirt/debris. Verify air intake lines are not kinked or restricted.
- Refer to DIAGNOSIS AND TESTING, 6.7L and perform the CHECKING THE INTAKE AIR SYSTEM PRESSURE diagnostic procedure.
- Inspect Turbocharger for wheel clearance and proper wastegate operation.
Were any problems found?
Yes
- Repair as necessary. Inspect and clean any soot fouling in the Air Handling and Exhaust systems as needed.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 28
- CHECKING THE EGR SYSTEM
- Perform the following EGR system checks:
- Look for visible signs (soot streaks) of an external EGR system leak.
- Remove the EGR Outlet Temperature Sensor from the thermostat outlet. Check the outlet for blockage or debris.
- Remove EGR Crossover Tube from EGR Cooler and EGR Valve. Inspect the tube for a restriction.
- Verify EGR Cooler is not leaking. Check for coolant in EGR plumbing, engine overheat fault codes, and low coolant level.
- Check the Air Intake Grid Heater for excessive soot build up or restriction.
Were any problems found?
Yes
- If the soot inside the EGR Crossover Tube is oily, inspect the Turbocharger for leaking oil into the intake system. If Turbo is leaking, replace the Turbo. If Turbo is not leaking, clean the Crossover Tube, remove and clean the EGR Valve and EGR Cooler. Also, inspect the valve guide seals for wear or leakage.
- Go To 29
No
- Go To 29
- Perform the following EGR system checks:
- CHECK THE EXHAUST AFTERTREATMENT SYSTEM FOR A RESTRICTION
- Perform the AFTERTREATMENT INSPECTION GUIDELINE procedure. Refer to AFTERTREATMENT INSPECTION GUIDELINE
.
Were any problems found during the inspection?
Yes
- Perform the appropriate repair.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Perform the DIESEL FUEL VALIDATION procedure. Refer to DIESEL AFTERTREATMENT VALIDATION . If the vehicles passes the validation, the vehicle is operating properly. If the vehicle fails the validation, the issue was missed during diagnostics.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
- Perform the AFTERTREATMENT INSPECTION GUIDELINE procedure. Refer to AFTERTREATMENT INSPECTION GUIDELINE
.