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

WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

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).

Turn the ignition switch to ON (II).
Clear the DTC with the HDS.
Start the engine.
Check for Pending 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 under-hood fuse/relay box (PGM-FI subrelay) and the PCM.
Turn the ignition switch to LOCK (0).
Check No. 11 A/F sensor (AFHT+) (15 A) fuse in the under-hood fuse/relay box.
Is the fuse OK?

YES -Go to step 7.

NO -Repair a short in the wire between the A/F sensors, the under-hood fuse/relay box (PGM-FI subrelay), then replace the blown fuse, then go to step 21.
Disconnect the secondary HO2S (Sensor 2) 4P connector.
At the sensor 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 5.4-6.6 Ω at room temperature (65-70 °F, 18-21 °C)?

YES -Go to step 9.

NO -Go to step 20.
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 20.

NO -Go to step 10.
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 a short in the wire between the PCM (C5 (C7)*) and the secondary HO2S (Sensor 2), then go to step 21.

NO -Go to step 13.
Check for continuity between secondary HO2S (Sensor 2) 4P connector terminal No. 3 and PCM connector terminal C5 (C7)*.

Fig 4: Checking Continuity Between Secondary HO2S (Sensor 2) 4P Connector Terminal No. 3 And PCM Connector Terminal C5 (C7)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 14.

NO -Repair an open in the wire between the PCM (C5 (C7)*) and the secondary HO2S (Sensor 2), then go to step 21.
Disconnect under-hood fuse/relay box connector H OP).
Check for continuity between secondary HO2S (Sensor 2) 4P connector terminal No. 4 and under-hood fuse/relay box connector H (9P) terminal No. 9.

Fig 5: Checking Continuity Between Secondary HO2S (Sensor 2) 4P Connector Terminal No. 4 And Under-Hood Fuse/Relay Box Connector H (9P) Terminal No. 9
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 16.

NO -Repair an open in the wire between the secondary HO2S (Sensor 2) and the under-hood fuse/relay box, then go to step 21.
Disconnect PCM connector A (49P).
Disconnect under-hood fuse/relay box connector E (14P).
Check for continuity between under-hood fuse/relay box connector E (14P) terminal No. 13 and PCM connector terminal A40.

Fig 6: Checking Continuity Between Under-Hood Fuse/Relay Box Connector E (14P) Terminal No. 13 And PCM Connector Terminal A40
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 19.

NO -Repair an open in the wire between the PCM (A40) and the under-hood fuse/relay box, then go to step 21.
Test the PGM-FI subrelay (built into the relay control module) (see RELAY CONTROL MODULE TEST ).
Is the PGM-FI subrelay OK?

YES -Go to step 27.

NO -Replace the under-hood fuse/relay box (see DTC B1065: RELAY CONTROL MODULE LOST COMMUNICATION WITH DRIVER'S MPCS UNIT (DRLOCKSW MESSAGE) ), then go to step 21.
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 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 under-hood fuse/relay box (PGM-FI subrelay), and the PCM, then go to step 1.

NO -Go to step 26.
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 or Confirmed DTCs were indicated in step 25, 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 under-hood fuse/relay box (PGM-FI subrelay), 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 ).
Start the engine, and let it idle.
Check for Pending 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 under-hood fuse/relay box (PGM-FI subrelay), and the PCM. If the PCM was updated, substitute a known-good PCM (see SUBSTITUTING THE PCM ), then go to step 29. If the PCM was substituted, go to step 1.

NO -Go to step 31.
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 or Confirmed DTCs were indicated in step 30, 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 under-hood fuse/relay box (PGM-FI subrelay), and the PCM. If the PCM was updated, substitute a known-good PCM (see SUBSTITUTING THE PCM ), then go to step 29. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, keep idling until a result comes on.