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Home >> Mazda >> 2007 >> 6 Mazdaspeed >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System L3 With TC] >> DTC P0401 >> Diagnostic procedure
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Diagnostic procedure

DTC P0401 DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED 
  • Have the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (EGR system related) been recorded?
 Yes Go to the next step.
No Record FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Check for related Service Bulletins and/or online repair information availability.
  • Is any related repair information available?
 Yes Perform the repair or diagnosis according to the available repair information.
  • If the vehicle is not repaired, go to the next step.
No Go to the next step.
3 INSPECT FOR OTHER DTCS 
  • Turn the ignition switch off then to the ON position (Engine off).
  • Have other DTCs been stored?
 Yes Repair the circuit malfunction for applicable DTCs.
No Go to the next step.
4 INSPECT VACUUM HOSE CONDITION 
  • Inspect freezing vacuum hoses for clogs, damage, frozen, or vacuum leakage.
  • Is there any malfunction?
 Yes Replace the vacuum hoses, then go to Step 8.
No Go to the next step.
5 INSPECT EGR VALVE MALFUNCTION 
 Yes Go to the next step.
No Replace the EGR valve, then go to Step 8.
6 INSPECT MAP SENSOR MALFUNCTION 
 Yes Go to the next step.
No Replace the MAP sensor, then go to Step 8.
7 INSPECT EGR VALVE PASSAGE 
  • Turn the ignition switch off.
  • Remove the EGR valve.
  • Is the gasket installation normal?
 Yes Go to the next step.
No Install the gasket correctly, then go to the next step.
8 MONITOR EGR SYSTEM BY DRIVE MODE 
  • Clear the DTC from the PCM memory using the WDS or equivalent.
  • Run the PCM Adaptive Memory Procedure Drive Mode.

    (See PCM ADAPTIVE MEMORY PRODUCTION DRIVE MODE ).

  • Stop the vehicle and access the ON BOARD READINESS TEST to inspect the DRIVE MODE completion status.
  • Verify the FUEL_EVAL and EGR_EVAL PIDs status.
  • Do the FUEL_EVAL and EGR_EVAL PIDs change to Yes?
 Yes Go to the next step.
No Retry this step.
9 VERIFY TROUBLESHOOTING OF DTC P0401 COMPLETED 
  • Make sure to reconnect all disconnected connectors.
  • Access the DIAGNOSTIC MONITORING TEST RESULTS.

    (See DIAGNOSTIC MONITORING TEST RESULTS ACCESS PROCEDURE ).

  • Verify the TEST #10: 31: 83 (EGR pressure variation) value.
  • Is the value within the specification?
 Yes Go to the next step.
No Replace the PCM, then go to the next step.
10 VERIFY AFTER REPAIR PROCEDURE 
 Yes Go to the applicable DTC inspection.
(See DTC TABLE ).
No Troubleshooting completed.
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