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DTC P0401-A: EGR System Failure

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
  1. Using scan tool, read Diagnostic Trouble Codes (DTCs). If scan tool display GLOBAL GOOD TRIP is equal to zero, go to step  4. If scan tool display GLOBAL GOOD TRIP is not equal to zero, go to next step.
  2. Using scan tool, read FREEZE FRAME data. Ensure hex code matches DTC on scan tool. Hex code should be 2E. If DTC matches hex code on scan tool, go to next step. If DTC does not match hex code on scan tool, repair DTC using FREEZE FRAME data. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
  3. Read FREEZE FRAME data on scan tool. Try to duplicate conditions identified on scan tool. Pay particular attention to code set conditions: engine RPM, coolant temperature and engine load. Using scan tool, observe GLOBAL GOOD TRIP counter. If GLOBAL GOOD TRIP counter changed to zero, go to next step. If GLOBAL GOOD TRIP counter does not change to zero, operate vehicle for one good trip, then erase DTCs. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
  4. Turn off all accessories. Start engine. Allow engine to reach operating temperature. Place scan tool in EGR SYSTEM TEST. Press No. 4 variable and ramp up EGR. Observe scan tool screen. If RPM changed in contrast to EGR status, go to step  7. If RPM did not change in contrast to EGR status, go to next step.
  5. Turn engine off. Remove EGR valve. Inspect exhaust manifold for restrictions. If any restrictions were found, repair or replace as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES . If no restrictions were found, go to next step.
  6. Remove tube from intake manifold. Remove tube from EGR valve assembly. Inspect tube for restrictions or leaks. If any restrictions or leaks were found, repair as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES . If no restrictions or leaks were found, replace EGR valve assembly. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
  7. Inspect EGR valve mounting area, EGR valve tightness and EGR valve gasket. Repair or replace EGR valve as necessary. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES . If no repairs were necessary, go to next step.
  8. Using scan tool, read FREEZE FRAME data. Ensure hex code matches DTC on scan tool. Hex code should be 2E. Utilize FREEZE FRAME data to help in diagnostics. Repair as necessary. Test is complete. Perform TEST VER-5A: ROAD TEST FOR OBD-II TROUBLE CODES .
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