DTC P0138, P0158 ('19 9-Speed A/T)

DTC P0138 : Rear Secondary Heated Oxygen Sensor (Secondary HO2S (Bank 1, Sensor 2)) Circuit High Voltage

DTC P0158 : Front Secondary Heated Oxygen Sensor (Secondary HO2S (Bank 2, Sensor 2)) Circuit High Voltage

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 Description	Confirmed DTC	Pending DTC
P0138 Rear Secondary Heated Oxygen Sensor (Secondary HO2S (Bank 1, Sensor 2)) Circuit High Voltage
P0158 Front Secondary Heated Oxygen Sensor (Secondary HO2S (Bank 2, Sensor 2)) Circuit High Voltage

DTC (PGM-FI)

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, then let it idle.

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

Signal	Threshold		Current conditions
Signal	Values	Unit	Values	Unit
HO2S B1 S2	More than 3.28	V
HO2S B2 S2 *	More than 3.28	V

Do the current condition (s) match the threshold?

YES

The failure is duplicated. Go to step 2.

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

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. Connect terminals A and B with a jumper wire.

Terminal A	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. 1 *:
Terminal B	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. 2 *:

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

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

- 4. Turn the vehicle to the ON mode.

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

Signal	Threshold		Current conditions
Signal	Values	Unit	Values	Unit
HO2S B1 S2	More than 3.28	V
HO2S B2 S2 *	More than 3.28	V

Do the current condition (s) match the threshold?

YES

Go to step 3.

Replace secondary HO2S (Sensor 2) .

Open wire check (SO2SGB1 (SO2SGB2) * line):

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

- 2. Remove the jumper wire from the secondary HO2S (Sensor 2) 4P connector.

- 3. Connect terminals A and B with a jumper wire.

Terminal A	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:
Terminal B	Body ground

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

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

- 4. Turn the vehicle to the ON mode.

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

Signal	Threshold		Current conditions
Signal	Values	Unit	Values	Unit
HO2S B1 S2	More than 3.28	V
HO2S B2 S2 *	More than 3.28	V

Do the current condition (s) match the threshold?

YES

Go to step 4.

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

Open wire check (SO2B1 (SO2B2) * line):

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

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

- 3. Disconnect the following connector.

PCM connector E (80P)

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

Test condition	Vehicle OFF (LOCK) mode
	Rear secondary HO2S (Bank 1, Sensor 2) 4P connector: disconnected
	Rear secondary HO2S (Bank 1, Sensor 2) 4P connector No. 2: jumped to body ground
	Front secondary HO2S (Bank 2, Sensor 2) 4P connector: disconnected *
	Front secondary HO2S (Bank 2, Sensor 2) 4P connector No. 1: jumped to body ground *
	PCM connector E (80P): disconnected
Test point 1	PCM connector E (80P) No. 56 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2019 2020 2021), or
Test point 1	PCM connector E (80P) No. 74 * - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2019 2020 2021),
Test point 2	Body ground

Is there continuity?

YES

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 - Refer to: PCM Removal and Installation (9-Speed A/T 2019 2020 2021), , then recheck. If DTC P0138 and/or P0158 * goes away and the PCM was substituted, replace the original PCM - Refer to: PCM Removal and Installation (9-Speed A/T 2019 2020 2021) .

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