Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0443

Evaporative Emission (EVAP) Purge Solenoid Valve Control Circuit

DTC P0458

Evaporative Emission (EVAP) Purge Solenoid Valve Control Circuit Low Voltage

DTC P0459

Evaporative Emission (EVAP) Purge Solenoid Valve Control Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition Voltage	P0443, P0458	P0443	-	-
EVAP Canister Purge Valve Control Circuit	P0458	P0443	P0459	-

Circuit/System Description

The evaporative emission (EVAP) canister purge valve is used to purge fuel vapor from the EVAP canister to the intake manifold. The EVAP canister purge valve is pulse width modulated (PWM). Ignition voltage is supplied directly to the EVAP canister purge valve. The engine control module (ECM) controls the solenoid by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

Conditions for Running the DTC

•	The engine speed is more than 80 RPM.

•	The ignition voltage is between 10-18 V.

•	The ECM has commanded the EVAP canister purge valve ON and OFF at least once during the ignition cycle.

•	The DTCs run continuously when the above conditions are met.

Conditions for Setting the DTC

P0443

The ECM detects the EVAP canister purge solenoid control circuit is open. The condition exists for 4 s or a cumulative of 30 s.

P0458

The ECM detects the EVAP canister purge solenoid control circuit is shorted to ground. The condition exists for 4 s or a cumulative of 30 s.

P0459

The ECM detects the EVAP canister purge solenoid control circuit is shorted to voltage. The condition exists for 4 s or a cumulative of 30 s.

Action Taken When the DTC Sets

DTC P0443, P0458 and P0459 are Type B DTCs.

Conditions for Clearing the DTC

DTC P0443, P0458 and P0459 are Type B DTCs.

Diagnostic Aids

If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool EVAP Purge Solenoid Circuit Test Status parameters for the component. A circuit test status parameter changes from OK or Not Run to Fault if there is a condition with the circuit or a connection.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Evaporative Emission Control System Description

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1.	Ignition ON, command the EVAP purge solenoid valve to 50 percent with a scan tool. You should hear an audible click.

2.	Engine operating, observe the scan tool EVAP Purge Solenoid Circuit Test Status parameters. Verify the parameters display OK or Not Run.

3.	Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. 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 purge solenoid Valve.

2.	Ignition ON, verify a test lamp illuminates between the ignition voltage circuit terminal 2 and ground.

3.	If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.

4.	Connect a test lamp between the control circuit terminal 1 and the ignition voltage circuit terminal 2.

5.	Note The control circuit for the EVAP purge solenoid is pulled-up to voltage within the ECM, 2.6-4.6 volts on the control circuit is normal. Command the EVAP purge solenoid valve to 50 percent and then to 0 percent with a scan tool. The test lamp should illuminate or flash and then go OFF.

6.	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.

7.	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.

8.	Test for 2.6-4.6 V between the control circuit terminal 1 and the K20 ECM.

9.	If the voltage is not within the specified range, replace the K20 ECM.

10.	If all circuits test normal, test or replace the Q12 EVAP purge solenoid.

Component Testing

1.	Ignition OFF, disconnect the harness connector at the Q12 EVAP purge solenoid valve. Test for 15-20 Ω between the terminals of the Q12 EVAP purge solenoid valve.

2.	If not within the specified range, replace the Q12 EVAP purge solenoid valve.

3.	Measure the resistance between each terminal of the Q12 EVAP purge solenoid valve and the EVAP purge solenoid valve housing. The DMM should display OL.

4.	If less than the specified value, replace the Q12 EVAP purge solenoid.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Evaporative Emission Canister Purge Solenoid Valve Replacement

•	Control Module References for ECM replacement, setup, and programming