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Home >> Mazda >> 2000 >> MX-5 Miata Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0401: Insufficient EGR Flow Detected >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

  1. Ensure FREEZE FRAME PID data has been recorded. Check service bulletins. Go to next step.
  2. Turn ignition off. Turn ignition on. If any other DTCs are present, diagnose and repair first. If no other DTCs are present, go to next step.
  3. Check for vacuum leaks. If no vacuum leaks are present, go to next step. If any vacuum leaks are present, diagnose and repair vacuum leak. Go to step  8.
  4. Start engine. Warm to operating temperature. Using scan tool in SIMULATION TEST mode, simulate SEGRP PID from zero to 18 steps. If engine speed decreases or stalls, go to next step. If engine speed does not change, replace EGR valve. Go to step  8.
  5. Turn engine off. turn ignition on. Disconnect EGR boost sensor vacuum hose. Connect vacuum pump to sensor. Using scan tool, check BARO V PID. Apply vacuum to sensor. If BARO PID voltage decreases, go to next step. If BARO PPID noes not change, replace EGR boost sensor. After repair, go to step  8.
  6. Start engine. Using scan tool in SIMULATION TEST mode, simulate EGRBV OFF. Vacuum should be present for 3 seconds at vacuum hose. If vacuum is not present, go to next step. If vacuum is present, replace sensor. After repair, go to step  8.
  7. Turn ignition off. Remove EGR valve. If gasket is installed normally, install EGR valve and go to next step. If gasket is not installed correctly, replace gasket, install EGR valve and go to next step.
  8. Clear DTC. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION - MIATA, MILLENIA, MPV & PROTEGE article. Perform DRIVE MODE No. 1. See DRIVE CYCLE PROCEDURE under SELF-DIAGNOSTICS - INTRODUCTION - MIATA, MILLENIA, MPV & PROTEGE article. Using scan tool, check RFC FLAG PID. If PID is ON, go to next step. If PID is OFF, clear codes and repeat DRIVE MODE No. 1.
  9. Perform DRIVE MODE No. 2. Using scan tool, check On-Board Readiness Test. If EGR system has been monitored, go to next step. If EGR system has not been monitored, repeat DRIVE MODE No. 2.
  10. Reconnect all connectors. Using scan tool, check diagnostic monitoring test results. If test No. 10:41:00 is within specification, go to next step. If test No. 10:41:00 is out of specification, replace PCM and go to next step.
  11. Erase DTC. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION - MIATA, MILLENIA, MPV & PROTEGE article. Conduct drive cycle mode. See DRIVE CYCLE PROCEDURE under SELF-DIAGNOSTICS - INTRODUCTION - MIATA, MILLENIA, MPV & PROTEGE article. Verify if any DTCs are stored or are present in PENDING TROUBLE CODE, DTC diagnostic monitoring test results. If no DTCs are present, testing is complete. If any DTCs are present, go to applicable test and repair.
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