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Home >> Mazda >> 2003 >> MPV ES >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0401: EGR Flow Insufficient Detected >> Diagnostic Procedures

Diagnostic Procedures

  1. Record freeze frame data. Check for service bulletins and on-line information. Repair as necessary. After repair, go to next step.
  2. Inspect For Other DTCs -  Turn ignition off, then on (engine off). If no other DTCs are present, go to next step. If any other DTCs are present, repair those DTCs first. Refer to DIAGNOSTIC TROUBLE CODE IDENTIFICATION .
  3. Inspect Vacuum Hose Condition -  Check all vacuum hoses for clogging, freezing, damage or leaks. If problems are not present, go to next step. If any problems are present, replace faulty vacuum hose(s). After repair, go to step  8.
  4. Inspect EGR Valve Malfunction -  Check EGR valve. See EXHAUST GAS RECIRCULATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article. If EGR valve is okay, go to next step. If EGR valve is faulty, replace EGR valve. After repair, go to step  8.
  5. Inspect EGR Boost Sensor Malfunction -  Check EGR boost sensor. See EXHAUST GAS RECIRCULATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article. If EGR boost sensor is okay, go to next step. If EGR boost sensor is faulty, replace EGR boost sensor. After repair, go to step  8.
  6. Inspect EGR Boost Sensor Solenoid Valve -  Check EGR boost sensor solenoid valve. See EXHAUST GAS RECIRCULATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - MAZDA6, MIATA, MPV, PROTEGE & PROTEGE5 article. If EGR boost sensor solenoid valve is okay, go to next step. If solenoid valve is faulty, replace EGR boost sensor solenoid valve. After repair, go to step  8.
  7. Inspect EGR Valve Passage -  Turn ignition off. Remove EGR valve. Inspect EGR passage for restriction or clogging. If EGR passage is restricted or clogged, clean passage as necessary. After repair, go to next step. If EGR passage is okay, inspect gasket installation. If gasket installation is okay, go to next step. If gasket is installed incorrectly, repair as necessary. After repair, go to next step.
  8. Monitor EGR System By Drive Mode 1 -  Reconnect all components. Turn ignition on, engine off. Using scan tool, clear DTC. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine. Perform MODE 1 - PCM ADAPTIVE MEMORY PRODUCE DRIVE MODE  under DRIVE MODES. Access RFC FLAG PID. If RFC FLAG PID is ON, go to next step. If RFC FLAG PID is OFF, repeat this step.
  9. Monitor EGR System By Drive Mode 2 -  Perform MODE 2 - EGR MONITOR REPAIR VERIFICATION DRIVE MODE  under DRIVE MODES. Using scan tool, access RFC FLAG PID. If RFC FLAG PID is ON, go to next step. If RFC FLAG PID is OFF, repeat this step.
  10. Verify Trouble Shooting Of DTC P0401 Completed -  Reconnect all components. Using scan tool, access DIAGNOSTIC MONITORING TEST RESULTS. Check TEST ID 10:41:00 value. If value is within specification, go to next step. If value is not within specification, replace PCM. After repair, go to next step.
  11. Verify After Repair Procedure -  Using scan tool, perform After Repair Procedure. See AFTER REPAIR PROCEDURE . If no other DTCs are present, testing is complete. If any other DTC is present, go to applicable test and repair.
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