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Home >> Acura >> 2004 >> MDX Base >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> PGM-FI System >> DTC Troubleshooting >> DTC P0141, P0161: Rear Secondary HO2S (Bank 1, Sensor 2) Heater Circuit Malfunction; Front Secondary HO2S (Bank 2, Sensor 2) Heater Circuit Malfunction

DTC P0141, P0161: Rear Secondary HO2S (Bank 1, Sensor 2) Heater Circuit Malfunction; Front Secondary HO2S (Bank 2, Sensor 2) Heater Circuit Malfunction

NOTE:
  • Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
  • Information marked with an asterisk (*) applies to the front bank (Bank 2).
  1. Turn the ignition switch ON (II).
  2. Clear the DTC with the HDS.
  3. Start the engine.
  4. Check for Temporary DTCs or DTCs with the HDS.

    Is DTC P0141 and/or P0161* indicated? 

    1. YES  - Go to step 5.
    2. NO  - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the PCM.
  5. Turn the ignition switch OFF.
  6. Check the No. 9 LAFHT (15 A) fuse in the underhood subfuse box.

    Is the fuse blown? 

    1. YES  - Repair short in the wire between the A/F sensors, the A/F sensor relay and the fuse, then go to step  24.
    2. NO  - Go to step 7.
  7. Disconnect the secondary HO2S (Sensor 2) 4P connector.
  8. At the secondary HO2S (Sensor 2) side, measure resistance between secondary HO2S (Sensor 2) 4P connector terminals No. 3 and No. 4.
    Fig 1: Measuring Resistance Between Secondary HO2S (Sensor 2) 4P Connector Terminals 3 And 4
    G03639715Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 5.4 - 6.6 Ω at room temperature? 

    1. YES  - Go to step 9.
    2. NO  - Go to step  23.
  9. Check for continuity between body ground and secondary HO2S (Sensor 2) 4P connector terminals No. 3 and No. 4 individually.
    Fig 2: Checking Continuity Between Body Ground And Secondary HO2S (Sensor 2) 4P Connector Terminals
    G03639716Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step  23.
    2. NO  - Go to step 10.
  10. Jump the SCS line with the HDS.
  11. Disconnect PCM connector A (73P).
  12. Check for continuity between PCM connector terminal A59 (A60)* and body ground.
    Fig 3: Checking Continuity Between PCM Connector Terminal A59 (A60)* And Body Ground
    G03639717Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Repair short in the wire between the PCM (A59 (A60)*) and the secondary HO2S (Sensor 2), then go to step  24.
    2. NO  - Go to step 13.
  13. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 3 to body ground with a jumper wire.
    Fig 4: Connecting Secondary HO2S (Sensor 2) 4P Connector Terminal 3 To Body Ground With Jumper Wire
    G03639718Courtesy of AMERICAN HONDA MOTOR CO., INC.
  14. Check for continuity between PCM connector terminal A59 (A60)* and body ground.
    Fig 5: Checking Continuity Between PCM Connector Terminal A59 (A60)* And Body Ground
    G03639719Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 15.
    2. NO  - Repair open in the wire between the PCM (A59 (A60)*) and the secondary HO2S (Sensor 2), then go to step  24.
  15. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 4 to body ground with a jumper wire.
    Fig 6: Connecting Secondary HO2S (Sensor 2) 4P Connector Terminal 4 To Body Ground With Jumper Wire
    G03639720Courtesy of AMERICAN HONDA MOTOR CO., INC.
  16. Remove the A/F sensor relay (A).
    Fig 7: Removing A/F Sensor Relay
    G03639721Courtesy of AMERICAN HONDA MOTOR CO., INC.
  17. Check for continuity between A/F sensor relay 4P connector terminal No. 2 and body ground.
    Fig 8: Checking Continuity Between A/F Sensor Relay 4P Connector Terminal 2 And Body Ground
    G03639722Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 18.
    2. NO  - Repair open in the wire between the secondary HO2S (Sensor 2) and the A/F sensor relay, then go to step  24.
  18. Disconnect PCM connector B (56P).
  19. Check for continuity between PCM connector terminal B10 and body ground.
    Fig 9: Checking Continuity Between PCM Connector Terminal B10 And Body Ground
    G03639723Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Repair short in the wire between the PCM (B10) and the A/F sensor relay, then go to step  24.
    2. NO  - Go to step 20.
  20. Connect A/F sensor relay 4P connector terminal No. 3 to body ground with a jumper wire.
    Fig 10: Connecting A/F Sensor Relay 4P Connector Terminal 3 To Body Ground With Jumper Wire
    G03639724Courtesy of AMERICAN HONDA MOTOR CO., INC.
  21. Check for continuity between PCM connector terminal B10 and body ground.
    Fig 11: Checking Continuity Between PCM Connector Terminal B10 And Body Ground
    G03639725Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 22.
    2. NO  - Repair open in the wire between the PCM (B10) and the A/F sensor relay, then go to step  24.
  22. Test the A/F sensor relay (see POWER RELAY TEST ).

    Is the A/F sensor relay OK? 

    1. YES  - Go to step  30.
    2. NO  - Replace the A/F sensor relay, then go to step  24.
  23. Replace the secondary HO2S (Sensor 2) (see SECONDARY HO2S REPLACEMENT  ).
  24. Reconnect all connectors.
  25. Turn the ignition switch ON (II).
  26. Reset the PCM with the HDS.
  27. Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
  28. Check for Temporary DTCs or DTCs with the HDS.

    Are any Temporary DTCs or DTCs indicated? 

    1. YES  - If DTC P0141 and/or P0161* is indicated, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the PCM, then go to step  1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
    2. NO  - Go to step 29.
  29. Monitor the OBD STATUS for DTC P0141 and/or P0161* in the DTCs MENU with the HDS.

    Does the screen indicate PASSED? 

    1. YES  - Troubleshooting is complete.
    2. NO  - If the screen indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the PCM, then go to step  1. If the screen indicates NOT COMPLETED, go to step  28 and recheck.
  30. Update the PCM if it does not have the latest software, or substitute a known-good PCM (see PCM UPDATING AND SUBSTITUTION FOR TESTING ).
  31. Check for Temporary DTCs or DTCs with the HDS.

    Are any Temporary DTCs or DTCs indicated? 

    1. YES  - If DTC P0141 and/or P0161* is indicated, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the PCM, then go to step  1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
    2. NO  - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM (see PCM REPLACEMENT  ).
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