P204B

DTC P204B Diesel Exhaust Fluid (DEF) Pressure Sensor Performance

Description

The DEF is drawn in from the DEF tank to the supply pump by operating an internal diaphragm type pump driven with the pump motor and it is sent to the DEF injector via the main filter and the pressure line. A pressurized excess DEF returns to the DEF tank via the branched backflow line within the supply pump housing. The DEF pressure sensor detects the DEF pressure in the backflow line between the main filter and the one-way valve. The DEF pressure should be fallen to nearly 0 psi (0 kPa) if the pressure reduction control or after run control is completed. The DEF control module detects this DTC if the DEF pressure does not stay within a specified pressure range when the DEF supply pump motor is commanded OFF.

Condition for Running the DTC

- DTCs P204C, P204D, P20E8, P20E9 and U0100 are not set.
- The battery voltage is between 10 to 16 volts.
- The ignition switch is ON.
- The intake air temperature 1 is more than 19 °F (-7 °C).

Condition for Setting the DTC

- The DEF control module detects that the DEF pressure is not within -7.3 to 7.3 psi (-50 to 50 kPa) longer than 4 seconds during the supply pump motor is commanded OFF.

Action Taken When the DTC Sets

- The DEF control module requests the ECM to illuminate the MIL on the second consecutive driving cycle. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type B.
- The DEF control module and the ECM apply defaulted warning actions and fail-safe controls. Refer to Default Action and Fail-Safe List.

Conditions for Clearing the DTC

- Refer to DTC Type Definitions for Conditions for Clearing the DTC - Type A or Type B.

Diagnostic Aids

Caution: Diesel Exhaust Fluid (DEF) is highly corrosive to electrical connectors and rubber used in electrical wiring. If any of these components come in contact with DEF, wash the area throughly with warm water and allow to completely dry before reconnection. Make a visual inspection for damage if the connection has been exposed to DEF.

- If an intermittent condition is suspected, refer to Intermittent Conditions in this section.

The DEF Supply Pressure on the scan tool cannot indicate a negative value.

Circuit / System Testing DTC P204B