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Home >> Chevrolet >> 2001 >> Impala LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.8L >> 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 powertrain diagnostic system check, go to next step.
  2. If any MAP DTCs are set, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no MAP DTCs are set, go to next step.
  3. Inspect exhaust system for modifications or leaks. If problem was found, repair as necessary. After repairs, go to step  7. If problem was not found, go to next step.
  4. Check EGR valve gasket and pipes for leaks. If problem was found, repair as necessary. After repairs, go to step  7. If problem was not found, go to next step.
  5. Remove EGR valve and check pintle, valve and passages and adapter for excessive deposits or restriction. If problem was found, repair as necessary. After repairs, go to step  7. If problem was not found, go to next step.
  6. Remove EGR inlet and outlet pipes from exhaust and intake manifolds. Inspect manifold EGR ports and pipes for blockage or damage. If problem was found, repair as necessary. After repairs, go to next step. If problem was not found, see DIAGNOSTIC AIDS .
  7. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria. If DTC runs and passes, go to next step. If DTC does not run and pass, go to step  2.
  8. Using scan tool, observe stored information. If scan tool displays any DTCs that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not display any DTCs, system is okay.
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