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Home >> Pontiac >> 2003 >> Aztek FWD >> 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. 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 P0107 or P0108 also set? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Inspect the exhaust system for modification of original installed parts or leaks. Repair the exhaust system as necessary. Did you find and correct the condition? If yes, go to step  7. If no, go to next step.
  4. Inspect for a vacuum leak between the EGR valve and intake manifold. Did you find and correct the condition? Did you find and correct the condition? If yes, go to step  7. If no, go to next step.
  5. Remove EGR valve. Visually and physically inspect the EGR pintle and EGR valve passages for leak or a restriction. Did you find and correct the condition? If yes, go to step  7. If no, go to next step.
  6. Remove the EGR inlet pipe from the exhaust manifold. Inspect the manifold EGR ports and EGR inlet pipe for blockage caused by excessive deposits or other damage. Correct the condition as necessary, if a problem is found. Did you find and correct the condition? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  7. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle within the Conditions for Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to step  2. If no, go to next step.
  8. 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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