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Home >> Isuzu >> 1997 >> Rodeo LS, 2.6 E >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 2.6L >> Circuit Testing >> DTC P0401 - EGR System Insufficient Flow >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. See BASIC TESTING article. Go to next step.
  2. If DTC P1406 is also set, go to DTC P1406. If DTC P1406 is not set, go to next step.
  3. Start engine and allow to idle. Using scan tool, monitor MAP signal. Push accelerator pedal half way and release quickly. If scan tool showed immediate large change in MAP value, go to next step. If scan tool did not show immediate large change in MAP value, replace MAP sensor. Retest system.
  4. Inspect exhaust system for modifications or leaks. If a problem is found, repair as necessary and go to step 7). If no problem is found, go to next step.
  5. Remove EGR valve and check pintle, valve and passages and adapter for excessive deposits or restriction. Check EGR valve gasket and pipes for leaks. If a problem is found, repair as necessary and go to step 7). If no problem is 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 a problem is found, repair as necessary and go to next step. If no problem is found, see DIAGNOSTIC AIDS  .
  7. Read and record FAIL RECORDS data for DTC P0401. Clear DTCs and monitor EGR TEST COUNT while operating vehicle within conditions noted in DIAGNOSTIC AIDS  until 9-12 test samples have been taken. Read SPECIFIC DTC. If scan tool displays DTC P0401 TEST RAN AND PASSED, repair is complete. If scan tool does not display DTC P0401 TEST RAN AND PASSED, return to step 2).
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