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Home >> Pontiac >> 2002 >> Aztek FWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0403: EGR Valve Control Circuit >> Diagnostic Procedures
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Diagnostic Procedures

  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. Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, command the EGR from 0 percent to 100 percent. Does the EGR position sensor remain close to the Desired EGR Position at all commanded positions? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC, or within the observed parameters of the Freeze Frame/Failure Records. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn OFF the ignition. Disconnect the EGR. Turn ON the ignition, with the engine OFF. Probe the EGR valve high control circuit with a test lamp connected to a good ground. With a scan tool, command the EGR between 0-10 percent. Does the test lamp turn ON and OFF with each command? If yes, go to next step. If no, go to step  6.
  5. Connect a test lamp between the EGR valve high control circuit and the EGR valve low control circuit. With a scan tool, command the EGR between 0-10 percent. Does the test lamp turn ON and OFF with each command? If yes, go to step  10. If no, go to step  9.
  6. Does the test lamp remain illuminated with each command? If yes, go to step  8. If no, go to next step.
  7. Test the EGR valve high control circuit for a short to ground or an open. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  8. Test the EGR valve high control circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  9. Test the EGR valve low control circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  10. Inspect for poor connections at the harness connector of the EGR valve. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  11. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace the EGR valve. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  14.
  13. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  14. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to step  2.
  15. 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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