DTC P0141: Rear Secondary HO2S (Bank 1, Sensor 2) Heater Circuit Malfunction; DTC P0161: 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).
Information marked with an asterisk (*1) applies to '09-11 models.
Information marked with an asterisk (*2) applies to '12 model.

Turn the ignition switch to ON (II).
Clear the DTC with the HDS.
Start the engine.
Check for Pending DTCs or Confirmed DTCs with the HDS.
Is DTC P0141 and/or P0161* indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), the under-dash fuse/relay box, and the PCM. ■
Turn the ignition switch to LOCK (0).
Check the No. 4 LAF (A/F SENSOR) (15 A) fuse in the under-dash fuse/relay box.
Is the fuse OK?

YES -Go to step 7.

NO -Go to step 22.
Test the A/F sensor relay (see POWER RELAY TEST ).
Is the fuse OK?

YES -Go to step 8.

NO -Replace the A/F sensor relay, then go to step 27.
Disconnect the secondary HO2S (Sensor 2) 4P connector.
At the secondary HO2S (Sensor 2) side, measure the 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 No. 3 And No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 5.4-7.3 O at room temperature (65-70°F, 18-21°C)?

YES -Go to step 10.

NO -Go to step 26.
At the sensor side, 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 No. 3 And No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 26.

NO -Go to step 11.
Jump the SCS line with the HDS.
Disconnect PCM connector C (49P).
Check for continuity between PCM connector terminal C5 (C7)* and body ground.

Fig 3: Checking Continuity Between PCM Connector Terminal C5 (C7) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair short in the wire between the PCM (C5 (C7) *) and the secondary HO2S (Sensor 2), then Go to step 27.

NO -Go to step 14.
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 No. 3 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between PCM connector terminal C5 (C7)* and body ground.

Fig 5: Checking Continuity Between PCM Connector Terminal C5 (C7) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 16.

NO -Repair open in the wire between the PCM (C5 (C7)*) and the secondary HO2S (Sensor 2), then Go to step 27.
Remove the A/F sensor relay (LAF) (A) from the under-dash fuse/relay box.

Fig 6: Identifying A/F Sensor Relay (LAF) From Under-Dash Fuse/Relay Box
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Connect secondary HO2S (Sensor 2) 4P connector terminal No. 4 to body ground with a jumper wire.

Fig 7: Connecting Secondary HO2S (Sensor 2) 4P Connector Terminal No. 4 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between A/F sensor relay (LAF) 4P connector terminal No. 2 and body ground.

Fig 8: Checking Continuity Between A/F Sensor Relay (LAF) 4P Connector Terminal No. 2 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 19.

NO -Repair open in the wire between the secondary HO2S (Sensor 2) and the A/F sensor relay (LAF), then Go to step 27.
Disconnect PCM connector A (49P).
Connect A/F sensor relay (LAF) 4P connector terminal No. 3 to body ground with a jumper wire.

Fig 9: Connecting A/F Sensor Relay (LAF) 4P Connector Terminal No. 3 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between PCM connector terminal A40 and body ground.

Fig 10: Checking Continuity Between PCM Connector Terminal A40 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 33.

NO -Repair open in the wire between the PCM (A40) and the A/F sensor relay (LAF), then Go to step 27.
Disconnect under-dash fuse/relay box connector X (39P).
Disconnect the EVAP canister vent shut valve 2P connector.
Disconnect the front and rear secondary HO2S (Sensor 2) 4P connectors.
Check for continuity between secondary HO2S (Sensor 2) 4P connector terminal No. 4 and body ground.

Fig 11: Checking Continuity Between Secondary HO2S (Sensor 2) 4P Connector Terminal No. 4 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short in the wire between the under-dash fuse/relay box and secondary HO2S (Sensor 2), then go to step 27.

NO -Check the under-dash fuse/relay box, and replace it if needed. Also replace the No. 4 LAF (A/F SENSOR) (15 A) fuse, then go to step 27.
Replace the secondary HO2S (Sensor 2) (see SECONDARY HO2S REPLACEMENT ).
Reconnect all connectors.
Turn the ignition switch to ON (II).
Reset the PCM with the HDS.
Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
Check for Pending DTCs or Confirmed DTCs with the HDS.
Is DTC P0141 and/or P0161* indicated?

YES -Check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the PCM, then Go to step 1.

NO -Go to step 32.
Monitor the OBD STATUS for DTC P0141 and/or P0161 * in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?

YES -Troubleshooting is complete. If any other Pending DTCs or Confirmed DTCs were indicated in step 31, Go to the indicated DTC's troubleshooting. ■

NO -If the HDS indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the PCM, then Go to step 1. If the HDS indicates NOT COMPLETED, keep idling until a result comes on.
Reconnect all connectors.
Update the PCM if it does not have the latest software (see PCM UPDATE ), or substitute a known-good PCM (see SUBSTITUTING THE PCM ).
Check for Pending DTCs or Confirmed DTCs with the HDS.
Is DTC P0141 and/or P0161* indicated?

YES -Check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the PCM. If the PCM was updated, substitute a known-good PCM (see SUBSTITUTING THE PCM ), then recheck. If the PCM was substituted, Go to step 1.

NO -Go to step 36.
Monitor the OBD STATUS for DTC P0141 and/or P0161 * in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?

YES -If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM (see PCM REPLACEMENT ). If any other Pending DTCs or Confirmed DTCs were indicated in step 31, Go to the indicated DTC's troubleshooting. ■

NO -If the HDS indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2), the A/F sensor relay (LAF), and the PCM. If the PCM was updated, substitute a known-good PCM (see SUBSTITUTING THE PCM ), then recheck. If the PCM was substituted, Go to step 1. If the HDS indicates NOT COMPLETED, keep idling until a result comes on.