LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mazda >> 2000 >> MPV DX >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0136: Middle Ho2S Malfunction >> Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0136: Middle Ho2S Malfunction: Testing

NOTE: Ensure freeze frame data has been recorded. Check for service bulletins and on-line information.
  1. Using scan tool, verify pending and stored DTCs. If any other DTCs are present, repair those DTC(s) first. If no DTCs are present, go to next step.
  2. Verify if DTC P0136 is present in FREEZE FRAME PID data. If DTC is present, go to next step. If DTC is not present in FREEZE FRAME PID data, go to TROUBLE SHOOTING - NO CODES article.
  3. Start engine. Warm engine to operating temperature. Using scan tool, access PID/DATA MONITOR. Monitor MHO2S. Depress accelerator pedal to WOT and release to race engine. Scan tool should display O2 sensor voltage greater than .45 volt during rich condition and less than .45 volt during lean condition. If voltage is not as specified, go to next step. If voltage is as specified, go to step  5 .
  4. Check O2 sensor installation. If sensor is loose, tighten sensor and go to step  12 . If sensor is tight, check for exhaust leaks upstream from O2 sensor. If any leaks are found, repair as necessary and go to step  12 . If no leaks are found, replace O2 sensor and go to step  12 .
  5. Using scan tool, access PID/DATA MONITOR. Compare LONGFT1 PID to FREEZE FRAME PID data. If fuel trim (LONGFT) is less than FREEZE FRAME DATA (shifting to rich condition), go to next step. If fuel trim is shifting to lean condition, go to step  8 .
  6. Turn ignition off. Check fuel system pressure. See BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is more than 45-51 psi, go to next step. If fuel pressure is 45-51 psi, go to step  11 .
  7. Disconnect vacuum line from fuel pressure regulator. Check for vacuum at disconnected line. If vacuum is present, check fuel pump maximum pressure. Check return line for clogging. If problem is found, repair as necessary. If no problem is found, replace fuel pressure regulator. After repairs, go to step  12 . If no vacuum is present, check vacuum line routing. Repair as necessary. If vacuum routing is okay, replace PRC solenoid. After repairs, go to step  12 .
  8. Turn ignition off. Check fuel system pressure. See BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is less than 45-51 psi, go to next step. If fuel pressure is 45-51 psi, go to step  11 .
  9. Check fuel system maximum pressure. See BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is 86-110 psi, go to next step. If fuel pressure is not 86-110 psi, check fuel pump circuit. If problem is found, repair as necessary. If no problem is present, replace fuel pump. After repair, go to step  12 .
  10. Check fuel system for leaks. If any leaks are found, repair as necessary and go to step 15. If no leaks are found, check fuel pump pickup screen and fuel filter. Replace as necessary. If no problems are found, replace fuel pressure regulator. After repair, go to step  12 .
  11. Check cooling system for combustion gasses. If no combustion gasses are present, go to next step. If combustion gasses are present, repair leak as necessary. After repair, go to next step.
  12. Reconnect all components. Turn ignition on. Erase DTC. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION - MIATA, MILLENIA, MPV & PROTEGE article. Conduct Drive Modes No. 1 and No. 3 under DRIVE CYCLE PROCEDURE. See SELF-DIAGNOSTICS - INTRODUCTION - MIATA, MILLENIA, MPV & PROTEGE article. Using scan tool, verify O2 sensor system readiness status. Check TEST #10:01:11, #10:02:11 or #10:03:11 in DIAGNOSTIC MONITORING TEST RESULTS. If any test exceeds MAX value, go to next step. If no test exceeds MAX value, replace PCM. PCM is mounted to passenger floor, behind glove box. After repair, go to next step.
  13. Perform after repair procedure. See AFTER REPAIR PROCEDURE  . If no DTC is present, testing is complete. If any DTC is present, go to appropriate test for diagnosis and repair.
scientia non olet · About LEMON Manuals