GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 Epica 🢒 Engine 🢒 Engine Controls - 2.5L (LBK) 🢒 DTC P0448

DTC Descriptors

DTC P0448: Evaporative Emission (EVAP) Vent Solenoid Valve 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) vent solenoid valve is used for EVAP system diagnostics. The EVAP vent solenoid valve is a normally open valve. Ignition voltage is supplied directly to the EVAP vent solenoid 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 running.
    • 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 vent solenoid control circuit.
    • The condition exists for less than 1 second.

Action Taken When the DTC Sets

DTC P0448 is a Type B DTCs.

Conditions for Clearing the DTC

DTC P0448 is a Type B DTCs.

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 P0448 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 vent 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.
  3. Test for 3.0-4.5  volts between the control circuit and ground.
    4. ⇒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.
  4. Ignition OFF, connect a 5-amp fused jumper wire to one terminal of the solenoid and the ignition 1 voltage circuit of the harness connector.

    5. Important: Listen for an audible sound or feel the solenoid body to determine if the solenoid activates.

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

Repair Instructions

Engine Control Module Replacement