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Home >> Chevrolet >> 1997 >> C3500 HD 7.4 J, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 3 (Engine Controls - Tests W/Codes - 6.5L) >> Diagnostic Trouble Codes >> DTC P0401 - EGR System Flow Insufficient >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. Perform Powertrain ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 6.5L DIESEL article. Then go to next step.
  2. Check if other EGR related DTCs are set. If other DTC(s) are present, diagnose affected DTC(s). If no other DTC(s) are present, go to next step.
  3. Check for plugged EGR ports, exhaust system leaks or for exhaust modifications. Repair as necessary. After repairs, go to next step.
  4. After repairs, reset EGR Adaptive Learn Matrix (ALM) using scan tool. After resetting EGR ALM, go to next step.
  5. Using scan tool, select CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC that was set. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
  6. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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