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Home › Saturn › 2003 › Ion 1 Automatic › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0448: EVAP Vent Valve Control Circuit Shorted › Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed form the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, refer to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L ION article.
  3. Turn OFF the ignition. Disconnect the EVAP canister vent solenoid. Inspect for poor connections at the EVAP canister vent solenoid. Did you find and correct the condition? If yes, go to step  9. If no, go to next step.
  4. Turn OFF the ignition. Connect a test light between the ignition 1 voltage circuit of the EVAP canister vent solenoid and the control circuit of the EVAP canister vent solenoid at the EVAP canister vent solenoid harness connector. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed form the Freeze Frame/Failure Records. Did DTC P0448 fail this ignition? If yes, go to next step. If no, go to step  7.
  5. Test the control circuit of the EVAP canister vent solenoid for a short to voltage. Did you find and correct the condition? If yes, go to step  9. If no, go to next step.
  6. Inspect for poor connections at the harness connector of the ECM. Did you find and correct the condition? If yes, go to step  9. If no, go to step  8.
  7. Replace EVAP canister vent solenoid. See EVAP CANISTER VENT SOLENOID under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL & INSTALLATION - ION article. After replacement, go to step  9.
  8. Replace ECM. See ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - ION article. Perform ECM relearn procedure. See ENGINE CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing ECM, go to next step.
  9. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  10. Using a scan tool, observe the CAPTURE INFO. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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