LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mazda >> 2000 >> MPV LX >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1169: Middle Oxygen Sensor, No Inversion >> Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P1169: Middle Oxygen Sensor, No Inversion: Testing

NOTE: Ensure freeze frame data has been recorded. Check for service bulletins and on-line information.
  1. Turn ignition off, then on. Verify stored DTCs. If no other DTCs are present, go to next step. If any other DTC is present, repair other DTC(s) first.
  2. Verify if DTC P1169 is present in FREEZE FRAME PID data. If DTC is present, go to next step. If DTC is not present, repair DTC(s) present in FREEZE FRAME PID data.
  3. 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 as specified, go to next step. If voltage is not as specified, replace O2 sensor and go to step  19 .
  4. Monitor LONGFT1 on FREEZE FRAME PID data. Compare to LONGFT1 in FREEZE FRAME DATA. If fuel trim is shifting to rich condition, go to next step. If fuel trim is shifting to lean condition, go to step  8 .
  5. 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  7 .
  6. 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  19 . If no vacuum is present, check vacuum line routing. If problem is found, repair as necessary. If vacuum routing is okay, replace PRC solenoid. After repairs, go to step  19 .
  7. Turn ignition off. Disconnect both vacuum hoses from purge solenoid valve. Blow air through valve. If air does not flow through valve, go to next step. If air flows through valve, replace purge solenoid valve. Go to step  12 .
  8. Turn ignition off. Check PCV system. See SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE & 626 article. If PCV system is okay, go to next step. If PCV system is faulty, repair as necessary. After repair, go to step  19 .
  9. 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  12 .
  10. 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  19 .
  11. Check fuel system for leaks. If any leaks are found, repair as necessary and go to step  19 . 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  19 .
  12. Start engine. Using an inductive timing light, check for steady flashing from each spark plug wire. If any wire does not cause steady flashing, go to next step. If all wires check okay, go to step  16 .
  13. Turn ignition off. Check suspect spark plug wire. If wire is okay, go to next step. If wire is faulty, replace wire. After repair, go to step  19 .
  14. Disconnect ignition coil connector. Turn ignition on. Check voltage between harness connector terminal "D" (Green/Black wire) and ground. If battery voltage is present, go to next step. If battery voltage is not present, repair open on circuit between connector and ignition switch. After repair, go to step  19 .
  15. Check ignition coil resistance. See BASIC DIAGNOSTIC PROCEDURES article. If coil is okay, go to next step. If coil is faulty, replace coil. After repair, go to step  19 .
  16. Check engine compression. If compression is okay, go to next step. If compression is low, repair as necessary. After repair, go to next step.
  17. Remove and check fuel injectors. See SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE & 626 article. If all injectors are okay, go to next step. If any injector (s) are faulty, replace as necessary. After repair, go to step  19 .
  18. 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.
  19. Reconnect all components. Start engine. Using scan tool, clear DTC. Ensure engine speed is more than 500 RPM, MAF PID is less than 1.09 lbs. min. and TP sensor input is less than 50 percent for at least 5 seconds. Recheck pending DTCs. If DTC P1123 is pending, replace PCM and go to next step. PCM is mounted to passenger floor, behind glove box. If DTC P1123 is not pending, go to next step.
  20. 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