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Home › Mazda › 2003 › B4000 Base, Automatic › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P1405 Or DTC P1406 › Diagnostic Procedures

Diagnostic Procedures

  1. If QUICK TEST was not performed, go to QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed, go to next step.
  2. Inspect Pressure Hose Connections -  If DTC P1406 is currently set, DTC P1408 will also appear in KOER Self-Test. Inspect upstream or downstream hose at DPFEGR sensor and orifice tube assembly for disconnect or poor connection. If hose is off or poorly connected, reconnect hose(s) or repair as necessary. After repair, go to step  6 . If hose is okay, go to next step.
    NOTE: It is essential that DPFEGR pressure hose is correct service part and not a substitute part.
  3. Inspect Pressure Hose For Plugging -  Visually inspect upstream or downstream hose routing. Hose should not be pinched or have dips where water could settle and freeze. Remove upstream or downstream hose and carefully inspect for plugging, water or leaks. If a problem is found with hose, repair or replace hose(s) as necessary. After repair, go to step  6 . If hose is okay, go to next step.
  4. Check Orifice Tube Assembly & DPFEGR Sensor -  Inspect connections at DPFEGR sensor for plugging or damage. Inspect exhaust and intake manifold side pressure pickup tube and orifice tube assembly for plugging, loose connection or damage. If a DPFEGR sensor or orifice tube assembly problem is found, repair or replace DPFEGR sensor or orifice tube assembly as necessary. After repair, go to step  6 . If DPFEGR sensor and orifice tube assembly is okay, go to next step.
  5. Check DPFEGR Sensor Output By Applying Vacuum With Hand Pump -  Disconnect pressure hoses at DPFEGR sensor. Connect a hand vacuum pump to downstream connection at sensor (intake manifold side or smaller diameter pickup tube). With KOEO, using scan tool, select DIAGNOSTIC DATA LINK. Select PCM. Select PID/DATA MONITOR AND RECORD. Access DPFEGR PID. Record reading. Apply 8-9 in. Hg (27-30 kPa) vacuum to DPFEGR sensor and hold for a few seconds. While observing DPFEGR PID, quickly release vacuum. DPFEGR PID voltage reading must be 0.2-1.3 volts with ignition on and no vacuum applied. DPFEGR PID voltage reading must increase to more than 4 volts with vacuum applied and drop to less than 1.5 volts in less than 3 seconds when vacuum is released. Turn ignition off. If DPFEGR PID voltage reading is within specification, replace faulty DPFEGR sensor. After repair, go to next step. If DPFEGR PID voltage reading is not within specification, fault is not present. See INTERMITTENT  testing under SYSTEM TESTS.
  6. Drive Cycle -  Reconnect all connectors. Using scan tool, clear DTC from PCM memory. Perform EVAP RUNNING LOSS SYSTEM REPAIR VERIFICATION DRIVE CYCLE  in MONITOR REPAIR VERIFICATION DRIVE CYCLES under DRIVE CYCLE PROCEDURES. Using scan tool, retrieve DTCs. If same DTC is not present, go to next step. If same DTC is present, replace faulty PCM. Go to next step.
  7. Verify Trouble Shooting Of DTCs Completed -  Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If any DTC is present, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS  under SELF-DIAGNOSTIC SYSTEM. If no DTC is present, trouble shooting is complete.
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