GM Service Manual Online
For 1990-2009 cars only

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 Descriptor

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

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition 1 Voltage

P0443

P0443

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EVAP Canister Purge Valve Control Circuit

P0443

P0443

P0443

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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 ignition is ON.
    • The ignition voltage is greater than 11 volts.
    • The DTCs runs continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects the EVAP purge solenoid control circuit is open, shorted to ground, or shorted to voltage.

Action Taken When the DTC Sets

DTC P0443 is a Type B DTC.

Conditions for Clearing the DTC

DTC P0443 is a Type B DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

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. Command the EVAP purge solenoid ON and OFF with a scan tool. You should hear the solenoid click when commanded ON and OFF.
  2. 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 EVAP purge solenoid.
  2. Ignition ON, verify a test lamp illuminates between the ignition 1 voltage circuit terminal 2 and ground.
  3. If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.
  4. Ignition OFF, connect a test lamp between the control circuit terminal 1 and the ignition 1 voltage circuit terminal 2.
  5. Ignition ON, command the EVAP purge solenoid ON and OFF with a scan tool. The test lamp should pulse ON and OFF with each command.
  6. If the test lamp is always ON, test the control circuit for a short to ground. If circuit tests normal, replace the ECM.
    If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal, replace the ECM.
  7. If all circuits test normal, test or replace the EVAP purge solenoid.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the EVAP purge solenoid.
  2. Test for 24-28 ohms of resistance between the control terminal 1 and the ignition 1 voltage terminal 2.
  3. If not within the specified range, replace the EVAP purge solenoid.
  4. Test for infinite resistance between each terminal and the EVAP purge solenoid housing.
  5. If not the specifed value, replace the 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 engine control module replacement, setup, and programming