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Home >> Pontiac >> 2001 >> Aztek Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0401: EGR System - Insufficient Flow >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. If any MAP related DTCs are set, diagnose affected DTCs first. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no MAP related DTCs are set, go to next step.
  3. Check exhaust system for modification of original installed parts or leaks. Repair as necessary. After repairs, go to step  7. If no problem is found, go to next step.
  4. Check EGR valve gasket and pipe for leaks. Repair or replace as necessary. After repairs, go to step  7. If no problem is found, go to next step.
  5. Remove EGR valve. Check for a leak and/or a restriction. Check EGR pintle and valve passages. Repair as necessary. After repairs, go to step  7. If no problem is found, go to next step.
  6. Remove EGR inlet pipe from exhaust manifold. Check manifold EGR ports and EGR inlet pipe for blockage caused by excessive deposits or other damage. Repair as necessary. After repairs, go to next step. If no problem is found, see DIAGNOSTIC AIDS .
  7. Turn ignition on, with engine off. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Operate vehicle within conditions for running this DTC. See CODE ENABLE CRITERIA . If DTC runs and passes, go to next step. If DTC resets, go to step  2.
  8. Using scan tool, observe the stored information and CAPTURE INFO. If scan tool displays any undiagnosed DTCs, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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