P20B1

DTC P20B1 Diesel Exhaust Fluid (DEF) Heater Valve Circuit Open

Circuit Description

The DEF control module controls the heater valve relay which supplies voltage to the DEF heater valve based on temperature signal inputs. The DEF heater valve opens internal valve and circulates the engine coolant to the DEF tank and the DEF supply pump under the specified temperature levels in order to defrost the DEF and keep it warm. The heater valve relay has a power supply circuit and a control circuit. The power supply circuit provides a battery voltage to the heater valve relay from the control module internal high side driver circuit, and the heater valve relay is energized through the control circuit by pulling the internal low side driver circuit to the ground when it is commanded ON. If the DEF control module detects an open circuit on the relay control circuit, this DTC will set.

Condition for Running the DTC

- The battery voltage is between 10 to 16 volts.
- The ignition switch is ON.

Condition for Setting the DTC

- The DEF control module detects an open circuit on the heater valve relay control circuit for 3 seconds.

Action Taken When the DTC Sets

- The DEF control module requests the ECM to illuminate the MIL. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type A.
- 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

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

Circuit / System Testing DTC P20B1