Diagnosis Procedure

WARNING: This page is about a different car, the 2018 Nissan Titan XD. However, it is still accessible from the selected car via links, so may be relevant.

CHECK DTC PRIORITY
1. Turn ignition switch ON.
2. Connect CONSULT and check for "ENGINE" diagnostic trouble codes.
3. Check for DTC P1C54-00 being current on the CONSULT screen.
Is applicable DTC detected?

YES

GO TO 2 .

NO

Refer to Intermittent Incident .
CHECK DTC PRIORITY
Check for current DTCs related to the aftertreatment intake NOx sensor and aftertreatment outlet NOx sensor on the CONSULT screen.

Is applicable DTC detected?

YES

Refer to DTC Index .

NO

GO TO 3 .
CHECK DTC PRIORITY
Check for current DTCs related to the aftertreatment SCR temperature sensor on the CONSULT screen.

Is applicable DTC detected?

YES

Refer to DTC Index .

NO

GO TO 4 .
CHECK DTC PRIORITY
Check for current DTCs related to the DEF dosing system and DEF quality sensor on the CONSULT screen.

Is applicable DTC detected?

YES

Refer to DTC Index .

NO

GO TO 5 .
CHECK EXHAUST SYSTEM FOR LEAKS
Check the exhaust system for leaks.
- Inspect the entire exhaust system between the turbocharger outlet and the SCR outlet.
- Inspect for loose connections and broken exhaust system components.
Are any leaks detected?

YES

Repair or replace damaged exhaust system components.

NO

GO TO 6 .
CHECK DEF DOSING SYSTEM FOR LEAKS
Inspect all components of the aftertreatment DEF dosing system for signs of external leaks.

NOTE: DEF will form white deposits around leaky fittings.
- DEF tank connectors.
- DEF dosing unit and dosing unit connectors.
- DEF lines.
- DEF dosing valve.
Are any leaks detected?

YES

Repair the source of the external leak.

NO

GO TO 7 .
CHECK DEF QUALITY
Check the DEF quality.
- Inspect the DEF in the tank for signs of debris or contamination.
- Test the DEF concentration using DEF Refractometer [SST: J-54466].
- DEF lines.
- DEF dosing valve.
Is the DEF free from contamination and DEF concentration within 32.5 A± 1.5%?

YES

GO TO 8 .

NO

Replace the DEF fluid.
CHECK DEF DOSING UNIT OPERATION
1. Connect all DEF lines and electrical connectors to the dosing unit and DEF tank.
2. Remove the aftertreatment DEF dosing using DEF valve from the decomposition tube.
3. Turn ignition switch ON.
4. Connect CONSULT and perform the "DEF doser pump override" in "Active Test".
  NOTE: DEF dosing valve must be placed in a measuring container in order to perform in "Active Test". Make sure valve is not plugged and DEF is flowing from all holes.
Does DEF dosing unit operate according to specifications?

YES

GO TO 9 .

NO

Replace aftertreatment DEF dosing unit. Refer to Removal and Installation .
CHECK DEF DOSING VALVE OPERATION
Perform the DEF system leak Active Test.

Is DEF leaking from valve during Active Test?

YES

Replace aftertreatment DEF dosing valve. Refer to Removal and Installation .

NO

GO TO 10 .
CHECK AFTERTREATMENT SYSTEM
1. Turn ignition switch OFF.
2. Inspect the decomposition tube for deposits.
  - Remove the decomposition tube.
  - Inspect for excessive DEF deposits.
Are any excessive DEF deposits detected?

YES

Clean and install the decomposition tube.

NO
- Replace the aftertreatment SCR catalyst. Refer to Exploded View .
- Replace the intake NOx sensor. Refer to Removal and Installation .
- Replace the outlet NOx sensor. Refer to Removal and Installation .
- GO TO 11 .
CHECK DTC PRIORITY
Check for current DTCs related to the aftertreatment intake NOx sensor and aftertreatment outlet NOx sensor on the CONSULT screen.
1. Turn ignition switch ON.
2. Connect CONSULT and check for "ENGINE" diagnostic trouble codes.
3. Check for DTC P1C54-00, P1C70-00 being current on the CONSULT screen.
Is applicable DTC detected?

YES

Recalibrate the ECM to the latest available calibration in order to clear the derate and allow the diagnostic to operate as intended..

NO

Refer to Intermittent Incident .