Diagnosis Procedure

1. Turn ignition switch ON.
2. Connect CONSULT and check for "ENGINE" diagnostic trouble codes.
3. Check for DTC P0420-00 being current on the CONSULT screen.

Is DTC P0420-00 detected as current?

YES

GO TO 2 .

NO

Refer to Intermittent Incident .

1. Turn ignition switch ON.
2. Connect CONSULT and check for "ENGINE" diagnostic trouble codes.
3. Are any of the following displayed as current on the CONSULT screen:
   • Any after treatment DOC temperature sensor or after treatment DPF temperature sensor DTCs
   • Any turbocharger DTCs
   • Any EGR valve DTCs
   • Any fuel system DTCs

Is applicable DTC detected?

YES

Refer to DTC Index .

NO

GO TO 3 .

1. Turn ignition switch OFF.
2. Inspect the exhaust system between the turbocharger outlet and the after treatment system:
   • Inspect for loose connections.
   • Inspect for leaking connections and broken exhaust system components.

Is the inspection result normal?

YES

GO TO 4 .

NO

Repair or replace error-detected parts.

1. Remove the after treatment DOC from the vehicle. Refer to Removal and Installation .
2. Inspect the after treatment DOC for:
   • Plugging from soot or oil contamination
   • Cracks or damage of any cells in the catalyst
   • Soot plugging the front face of the catalyst

Is the inspection result normal?

YES

GO TO 5 .

NO

Repair or replace the after treatment DOC.

1. Remove the exhaust plumbing from the turbocharger outlet.
2. Inspect the turbocharger exhaust outlet for signs of oil, coolant, or fuel being introduced into the after treatment system.

Is the inspection result normal?

YES

GO TO 6 .

NO

Locate and repair the cause of possible diesel fuel, coolant, or engine oil being carried from the engine into the after treatment system.

1. Disconnect exhaust pipe from turbocharger outlet.
2. Start the engine.
3. Perform the Snap Acceleration - After treatment Disconnected procedure to check for excessive black smoke. Refer to Work Procedure .

Is the inspection result normal?

YES

Inspection End.

NO

Refer to appropriate engine performance symptom table. Refer to Symptom Table .