Diagnosis Procedure

1. Turn ignition switch ON.
2. Connect CONSULT and check for existing "ENGINE" diagnostic trouble codes.
3. Check for DTC P204A-00 current on the CONSULT screen.

Is applicable DTC current?

YES

GO TO 2 .

NO

Refer to Intermittent Incident .

1. Make sure the aftertreatment DEF tank is not empty and the tank level gauge is accurate.
2. Using CONSULT check for other ENGINE diagnostic trouble codes.

Is P203F-00 DTC current?

YES

Fill the DEF tank.

NO

GO TO 3 .

1. Turn ignition switch OFF.
2. Check the DEF tank for debris or foreign particles.
3. Check the DEF tank vent for crystallization buildup and clogging.

Is the inspection result normal?

YES

GO TO 4 .

NO

Clean the DEF tank thoroughly and fill with certified DEF.

1. Turn ignition switch ON.
2. Using CONSULT check for the following "ENGINE" diagnostic trouble codes:
   • P204C-00
   • P204D-00
   • P20E8-00
   • P20E9

Are any of the above DTCs current?

YES

Refer to DTC Index .

NO

GO TO 5 .

1. Turn ignition switch OFF.
2. Inspect the DEF line on the selective catalytic reduction (SCR) dosing system.
3. Inspect dosing valve supply line between the dosing unit and dosing valve (pressure line).
4. Inspect the DEF line and associated fittings or connectors:
   • Check the DEF tank connections for cracks and pitting.
   • Check the dosing unit connections and fittings for loose, leaking, or damaged connections.
   • Disconnect the pressure line dosing unit connectors and look for signs of buildup or blockage.
   • Verify proper sealing at all connection points, including DEF tank, dosing unit, and dosing valve.

Any damaged, leaking, or restricted connections found?

YES

Repair or replace the leaking DEF line or fitting, or replace the DEF dosing unit as necessary.

NO

GO TO 6 .

1. Turn ignition switch ON.
2. Connect CONSULT.
3. Check for air in the DEF.

Is air found in the DEF?

YES

Check the DEF dosing unit fittings, pressure line fittings, tank fittings and repair as necessary.

NO

GO TO 7 .

1. Turn ignition switch OFF.
2. Remove the tank level and temperature sensor from the DEF tank.
3. Inspect the aftertreatment DEF tank filter for signs of blockage or buildup.

Is the DEF tank filter blocked?

YES

Drain, clean, and refill the DEF tank.

NO

GO TO 8 .

1. Connect all harness connectors.
2. Remove the aftertreatment DEF dosing valve from the decomposition tube.
3. Place the DEF dosing valve in a measuring container having greater than a 1.5 liter [50 oz] capacity.
4. Turn ignition switch ON.
5. Using CONSULT, access "ENGINE" and select "DEF Dosing Unit Override Test" active test.

Did the DEF dosing unit operate according to specifications?

YES

GO TO 9 .

NO

Replace the DEF supply pump assembly. Refer to Exploded View .

1. Turn ignition switch OFF.
2. Connect all harness connectors.
3. Turn ignition switch ON.
4. Using CONSULT, select "ENGINE" and clear DTCs.
5. Operate the engine within the "Conditions for Clearing the DTC" found in the DTC description of this diagnosis procedure.

Is P204A-00 DTC current?

YES

Diagnosis procedure needs to be repeated. Refer to DTC Description .

NO

Repair complete.