GM Service Manual Online
For 1990-2009 cars only

DTC Descriptors

DTC P0445: Evaporative Emission (EVAP) Purge Solenoid Control Circuit Shorted.

Diagnostic Fault Information

Perform the Diagnostic System Check - Engine Controls prior to using this diagnostic procedure.

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 or the engine is operating.
    • The DTC runs continuously once the above conditions are met.

Conditions for Setting the DTC

    • The ECM detects a short to ground or a short to voltage on the EVAP canister purge valve control circuit.
    • The condition exists for less than 1 second.

Action Taken When the DTC Sets

DTCP0445 is a Type B DTC.

Conditions for Clearing the DTC

DTCP0445 is a Type B DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification

  1. Engine idling, observe the DTC information with a scan tool. DTC P0445 should not set.
  2. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector of the EVAP purge solenoid.
  2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit 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 circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.
  4. Test for 3.0-4.5  volts between the control circuit and ground.
  5. If less than 3.0 volts, test the control circuit for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.
    If greater than 4.5 volts, test the control circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
  6. Ignition OFF, connect a 5-amp fused jumper wire to one terminal of the solenoid and B+.
  7. Important: Listen for an audible sound or feel the solenoid body to determine if the solenoid activates.

  8. Connect a jumper wire to the other terminal of the solenoid and ground. The solenoid should turn ON.
  9. If the solenoid remains OFF, replace the solenoid.
  10. If all circuits/connections test normal, replace the ECM.

Repair Instructions

    •  Evaporative Emission Canister Purge Solenoid Valve Replacement
    •  Engine Control Module Replacement