P208B

DTC P208B Diesel Exhaust Fluid (DEF) Pump 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. The DEF pressure is kept near constant pressure by controlling speed of the pump motor. The DEF control module monitors actual pump motor speed using a sensor attached to the pump motor and compares with a target speed continuously. If the DEF control module detects that the difference between the actual and the target pump motor speed is greater than a predetermined range, this DTC will set.

Condition for Running the DTC

- 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).
- The pump motor is commanded ON.

Condition for Setting the DTC

- The DEF control module detects that the difference between the actual and target pump motor speed is greater than a predetermined speed.

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.
- Low system voltage may set this DTC.
- Cover on the DEF tank and the DEF supply pump must be attached for keeping them warm.
- Normal DEF Supply Pressure on the scan tool during the DEF supply pump operating is nearly 130 psi (900 kPa).

Circuit / System Testing DTC P208B