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Diagnostic Procedures

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  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Is DTC P1656 also set? If yes, see DTC P1654: WASTEGATE SOLENOID CONTROL CIRCUIT  . If no, go to next step.
  3. Disconnect the vacuum line at the turbocharger wastegate actuator. Install a vacuum gauge in place of the turbocharger wastegate actuator. Start the engine. Observe the vacuum at idle. Is the vacuum more than or equal to 15 in. Hg (the vacuum will fluctuate)? If yes, go to next step. If no, go to step  6 .
  4. With the engine still running, disconnect the wastegate solenoid electrical connector. With the vacuum gauge still in place, observe the vacuum gauge at idle. Does the vacuum measure more than 1 in. Hg? If yes, go to step  12 . If no, go to next step.
  5. Turn OFF the engine. Connect a hand-held vacuum pump to the turbocharger wastegate actuator. Apply 5 in. Hg of vacuum. Does the turbocharger wastegate actuator hold vacuum? If yes, go to step  7 . If no, go to step  14 .
  6. Check all of the vacuum lines from the vacuum pump to the turbocharger wastegate actuator for:
    • Leaks Deformities
    • Pinches

    If you find a problem, repair the condition as necessary. Did you find a problem? If yes, go to step  15 . If no, go to step  8 .

  7. Verify that the engine is OFF. Disconnect all the vacuum lines to the wastegate actuator. Grip the wastegate actuator rod with a pair of pliers. Attempt to move the wastegate actuator rod back and forth. Does the turbocharger wastegate actuator rod move freely? If yes, go to next step. If no, go to step  14 .
  8. Check the vacuum pump for proper output. See appropriate SYSTEM & COMPONENT TESTING article. Did you find a problem? If yes, go to step  15 . If no, go to next step.
  9. Connect a scan tool. Start the engine and let the engine idle. Observe the boost pressure display on the scan tool. Increase the engine RPM to 1500, and return the engine to an idle. Does the scan tool display a change in boost pressure? If yes, go to next step. If no, go to step  11 .
  10. The DTC is intermittent. If no additional DTCs are stored, see DIAGNOSTIC AIDS  . If any additional DTCs are stored, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  .
  11. Replace the boost sensor. After repairs, go to step  16 .
  12. Check for a plugged wastegate solenoid filter. Is the wastegate solenoid filter plugged? If yes, go to step  16 . If no, go to next step.
  13. Replace the wastegate solenoid. After repairs, go to step  16 .
  14. Replace the turbocharger wastegate actuator. After repairs, go to step  16 .
  15. Replace the vacuum pump. After repairs, go to next step.
  16. Using the scan tool, clear the DTCs. Start engine and idle the engine at the normal operating temperature. Select DTC and the Specific DTC function. Enter the DTC number that was set. Operate the vehicle within the Conditions for Setting DTC until the scan tool indicates the diagnostic ran. Does the scan tool indicate the diagnostic passed? If yes, go to next step. If no, go to step  2 .
  17. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, system is okay.
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