DTC P2A01, P2A04 (19-21 9-Speed A/T)

DTC P2A01  : Rear Secondary Heated Oxygen Sensor (Secondary HO2S) (Bank 1, Sensor 2) Circuit Range/Performance Problem

DTC P2A04  : Front Secondary Heated Oxygen Sensor (Secondary HO2S) (Bank 2, Sensor 2) Circuit Range/Performance Problem

NOTE: 

• Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Fuel and Emissions Systems, .
• Information marked with an asterisk (*) applies to the front bank (Bank 2).

DTC (PGM-FI)

1. Problem verification

   - 1. Turn the vehicle to the ON mode.

   - 2. Clear the DTC with the HDS.

   - 3. Turn the vehicle to the OFF (LOCK) mode.

   - 4. Start the engine.

   - 5. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan comes on.

   - 6. Monitor the OBD STATUS for DTC P2A01 and/or P2A04 * in the DTCs MENU with the HDS.

   DTC Description	OBD STATUS
   P2A01 Rear Secondary Heated Oxygen Sensor (Secondary HO2S) (Bank 1, Sensor 2) Circuit Range/Performance Problem
   P2A04 Front Secondary Heated Oxygen Sensor (Secondary HO2S) (Bank 2, Sensor 2) Circuit Range/Performance Problem

   Does the HDS indicate FAILED?

   YES 

   The failure is duplicated. Go to step 2.

   NO 

   If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the PCM.

   If the on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot - Refer to: How to Troubleshoot the Fuel and Emissions Systems, .

   If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 1-5 and recheck.

2. Determine possible failure area (Secondary HO2S (Sensor 2), others)

   - 1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the following connector.

   Secondary HO2S (Sensor 2) 4P connector

   - 3. Turn the vehicle to the ON mode.

   - 4. Check the parameter (s) below with the HDS.

   Signal	Threshold		Current conditions
   	Values	Unit	Values	Unit
   HO2S B1 S2	Less than 1.54	V
   HO2S B2 S2	Less than 1.54	V

   Do the current condition (s) match the threshold?

   YES 

   Go to step 3.

   NO 

   Replace secondary HO2S (Sensor 2) .

3. Determine possible failure area (short in SO2B1 (SO2B2) * line, short in SO2SGB1 (SO2SGB2) * line):

   - 1.Turn the vehicle to the OFF (LOCK) mode.

   - 2. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Secondary HO2S (Sensor 2) 4P connector: disconnected
   Test point 1	Rear secondary HO2S (Bank 1, Sensor 2) 4P connector (female terminals) No. 2:
   	Front secondary HO2S (Bank 2, Sensor 2) 4P connector (male terminals) No. 1 *:
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   Go to step 4.

   NO 

   Go to step 5.

4. Shorted wire check (SO2B1 (SO2B2) * line):

   - 1.Jump the SCS line with the HDS, and wait more than 1 minute.

   - 2. Disconnect the following connector.

   PCM connector E (80P)

   - 3. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Secondary HO2S (Sensor 2) 4P connector: disconnected
   	PCM connector E (80P): disconnected
   Test point 1	Rear secondary HO2S (Bank 1, Sensor 2) 4P connector (female terminals) No. 2:
   	Front secondary HO2S (Bank 2, Sensor 2) 4P connector (male terminals) No. 1 *:
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   Repair a short in the SO2B1 (SO2B2) * wire between the PCM (E56 (E74) *) and secondary HO2S (Sensor 2).

   NO 

   The SO2B1 (SO2B2) * wire is OK.

   Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM, then recheck. - Refer to: PCM Removal and Installation (9-Speed A/T) (2019 2020 2021) .

   If DTC P2A01 and/or P2A04 * goes away and the PCM was substituted, replace the original PCM - Refer to: PCM Removal and Installation (9-Speed A/T) (2019 2020 2021) .

5. Shorted wire check (SO2SGB1 (SO2SGB2) * line):

   - 1.Jump the SCS line with the HDS, and wait more than 1 minute.

   - 2. Disconnect the following connector.

   PCM connector E (80P)

   - 3. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Secondary HO2S (Sensor 2) 4P connector: disconnected
   	PCM connector E (80P): disconnected
   Test point 1	Rear secondary HO2S (Bank 1, Sensor 2) 4P connector (female terminals) No. 1:
   	Front secondary HO2S (Bank 2, Sensor 2) 4P connector (male terminals) No. 2 *:
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   Repair a short in the SO2SGB1 (SO2SGB2) * wire between the PCM (E57 (E75) *) and secondary HO2S (Sensor 2).

   NO 

   The SO2SGB1 (SO2SGB2) * wire is OK.

   Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM, then recheck. - Refer to: PCM Removal and Installation (9-Speed A/T) (2019 2020 2021)

   If DTC P2A01 and/or P2A04 * goes away and the PCM was substituted, replace the original PCM - Refer to: PCM Removal and Installation (9-Speed A/T) (2019 2020 2021) .