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 FOR CURRENT DEF LINE HEATER CIRCUIT DTC
Check for DTC P20BB-00 current on the CONSULT screen.

Is applicable DTC current?

YES

GO TO 2 .

NO

Refer to Intermittent Incident .
INSPECT DEF CONTROL MODULE AND CONNECTOR PINS
1. Turn ignition OFF.
2. Disconnect the DEF control module.
3. Inspect both connectors for the following:
  - Loose connector.
  - Corroded pins.
  - Bent or broken pins.
  - Pushed back or expanded pins.
  - Moisture in or on the connector.
  - Missing or damaged connector seals.
  - Dirt or debris on or in the connector pins.
  - Connector shell broken.
  - Wire insulation damage.
  - Damaged connector locking tab.
Is the inspection result normal?

YES

GO TO 3 .

NO

Repair or replace error-detected parts.

CHECK DEF LINE HEATER POWER CIRCUIT FOR SHORT TO GROUND

Disconnect the DEF line heater from the harness.
Check for continuity between DEF line heater power circuit at the DEF control module and ground.

DEF control module			Continuity
Connector	Terminal	Terminal	Continuity
C205	15	Ground	No

Is the inspection result normal?

YES

GO TO 4 .

Repair short circuit in harness connector.

CHECK DEF LINE HEATER GROUND CIRCUIT FOR SHORT TO GROUND

Check for continuity between DEF line heater ground circuit at the DEF control module and ground.

DEF control module			Continuity
Connector	Terminal	Terminal	Continuity
C205	30	Ground	No

Is the inspection result normal?

YES

GO TO 5 .

Repair short circuit in harness connector.

CHECK DEF LINE HEATER POWER CIRCUIT FOR SHORT TO OTHER CIRCUITS

Check for continuity between DEF line heater power circuit at the DEF control module and all other circuits.

DEF control module			Continuity
Connector	Terminal	Terminal	Continuity
C205	15	All others	No

Is the inspection result normal?

YES

GO TO 6 .

Repair short circuit in harness connector.

CHECK DEF LINE HEATER GROUND CIRCUIT FOR SHORT TO OTHER CIRCUITS

Check for continuity between DEF line heater ground circuit at the DEF control module and all other circuits.

DEF control module			Continuity
Connector	Terminal	Terminal	Continuity
C205	30	All others	No

Is the inspection result normal?

YES

GO TO 7 .

Repair short circuit in harness connector.

CHECK FOR CURRENT DTC
1. Connect all harness connectors.
2. Turn ignition switch ON.
3. Connect CONSULT and erase "ENGINE" diagnostic trouble codes.
4. Using CONSULT, activate "DEF Line Heater Test".
5. The DTC will move to "Past" when the test runs and passes.
Is P20BB-00 DTC current?

YES

A malfunctioning line heater has been detected. Replace the DEF line heater. Refer to Removal and Installation .

NO

A malfunctioning DEF control module has been detected. Replace the DEF control module. Refer to Removal and Installation .