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Home >> Mazda >> 2010 >> 5 Touring, 2.3 L >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System L3] >> DTC P0401 >> Diagnostic procedure
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Diagnostic procedure

DTC P0401 [L3] DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA (MODE 2) 
  • Is DTC P0401 on FREEZE FRAME DATA (Mode 2)?
 Yes Go to the next step. '
No Go to troubleshooting for DTC on FREEZE FRAME DATA (Mode 2).
(See DTC TABLE .)
2 VERIFY FREEZE FRAME DATA (MODE 12) AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED 
  • Have FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS (EGR system related) been recorded?
 Yes Go to the next step.
No Record FREEZE FRAME DATA (Mode 12) and DIAGNOSTIC MONITORING TEST RESULTS on repair order, then go to the next step.
3 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Verify related Service Bulletins and/or on-line repair information availability.
  • Is any related repair information available?
 Yes Perform repair or diagnosis according to available repair information.
  • If vehicle is not repaired, go to the next step.
No Go to the next step.
4 INSPECT FOR OTHER DTCS 
  • Turn the ignition switch off then to the ON position (Engine off).
  • Have other DTCs been stored?
 Yes Repair circuit malfunction for applicable DTCs.
No Go to the next step.
5 INSPECT VACUUM HOSE CONDITION 
  • Inspect vacuum hoses for clogs, any damages, frozen, or vacuum leakage.
  • Is there any malfunction?
 Yes Replace vacuum hoses, then go to Step 9.
No Go to the next step.
6 INSPECT EGR SYSTEM OPERATION 
 Yes Go to the next step.
No Repair or replace malfunctioning part according to inspection result, then go to Step 9.
7 INSPECT MAP SENSOR MALFUNCTION 
 Yes Go to the next step.
No Replace MAP sensor, then go to Step 9.
8 INSPECT EGR VALVE PASSAGE 
  • Turn the ignition switch off.
  • Remove the EGR valve.
  • Visually inspect the gasket installation of EGR valve passage for clogging.
  • Is there any malfunction?
 Yes Repair or replace malfunctioning part according to inspection result, then go to the next step.
No Go to the next step.
9 MONITOR EGR SYSTEM BY DRIVE MODE 
  • Clear DTC from PCM memory using M-MDS.
  • Run EGR system repair verification drive mode.

    (See OBD-II DRIVE MODE .)

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

    (See ON-BOARD DIAGNOSTIC TEST .)

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