Diagnostic Instructions

DTC Descriptors

DTC P0443: Evaporative Emission (EVAP) Purge Solenoid Control Circuit

DTC P0458: Evaporative Emission (EVAP) Purge Solenoid Control Circuit Low Voltage

DTC P0459: Evaporative Emission (EVAP) Purge Solenoid Control Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance/Open	Short to Voltage
Ignition 1 Voltage - Purge Supply	P0443	P0443	--
EVAP Purge Solenoid Control	P0458	P0443	P0459

Circuit/System Description

An ignition voltage is supplied directly to the evaporative emission (EVAP) canister purge solenoid valve. The engine control module (ECM) grounds the EVAP canister purge solenoid valve control circuit through an internal switch called a driver. The ECM monitors the status of the driver. The EVAP canister purge solenoid valve is pulse width modulated (PWM). A scan tool will display the amount of ON time as a percentage.

Conditions for Running the DTC

Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match, for up to 0.5 second.

Action Taken When the DTC Sets

DTCs P0443, P0458, and P0459 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0443, P0458, and P0459 are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

With the ignition ON, engine OFF, you should hear a clicking sound when the EVAP canister purge solenoid valve is commanded to 50 percent with a scan tool. The clicking sound should stop when the EVAP canister purge solenoid valve is commanded to 0 percent. The rate at which the valve cycles should increase when the commanded state is increased, and decrease when the commanded state is decreased. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the Q12 EVAP canister purge solenoid valve.
2. Ignition ON, verify that a test lamp illuminates between the voltage supply circuit terminal A and ground.

⇒	If the test lamp does not illuminate, test the volage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and the voltage supply circuit fuse is open, test or replace the Q12 EVAP canister purge solenoid valve.

3. Connect a test lamp between the voltage supply circuit terminal A and the control circuit terminal B.
4. Command the EVAP canister purge solenoid valve to 50 percent with a scan tool. The test lamp should respond to the command.

⇒	If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

5. If all circuits test normal, replace the Q12 EVAP canister purge solenoid valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.