DTC P0135, P0155 (6-Speed A/T, '16-'18 9-Speed A/T)

DTC P0135 : Rear A/F Sensor (Bank 1, Sensor 1) Heater Circuit Malfunction

DTC P0155 : Front A/F Sensor (Bank 2, Sensor 1) Heater Circuit Malfunction

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	Freeze Frame
P0135 Rear A/F Sensor (Bank 1, Sensor 1) Heater Circuit Malfunction
P0155 Front A/F Sensor (Bank 2, Sensor 1) Heater Circuit Malfunction

DTC (PGM-FI)

Problem verification

-1. Turn the vehicle to the ON mode.

- 2. Clear the DTC with the HDS.

- 3. Start the engine.

- 4. Check for Pending or Confirmed DTCs with the HDS.

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P0135 Rear A/F Sensor (Bank 1, Sensor 1) Heater Circuit Malfunction
P0155 Front A/F Sensor (Bank 2, Sensor 1) Heater Circuit Malfunction

Is DTC P0135 and/or P0155 * indicated?

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 the A/F sensor (Sensor 1), the relay circuit board (PGM-FI subrelay circuit), and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot - Refer to: How to Troubleshoot the Fuel and Emissions Systems

Fuse check

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

- 2. Check the following fuse.

Fuse	No. A22 (15 A)
Location	Under-hood fuse/relay box

Is the fuse OK?

YES

Go to step 3.

Go to step 11.

Relay circuit board check
-1. Remove and test the relay circuit board.

Is the relay circuit board OK?

YES

Go to step 4.

NO

Replace the relay circuit board .

A/F sensor (Sensor 1) internal heater resistance check

-1. Disconnect the following connector.

A/F sensor (Sensor 1) 6P connector

- 2. At the sensor side, measure the resistance between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit board: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
Test point 1	A/F sensor (Sensor 1) 6P connector No. 2 (A/F sensor (Sensor 1) side)
Test point 2	A/F sensor (Sensor 1) 6P connector No. 3 (A/F sensor (Sensor 1) side)

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

Is there 5.4-6.6 Ω at room temperature?

YES

Go to step 5.

Replace the A/F sensor (Sensor 1) .

A/F sensor (Sensor 1) internal circuit check 1

-1. Check for continuity between the following test points and body ground individually.

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit board: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected

Connector

Test circuit

Terminal

A/F sensor (Sensor 1) (A/F sensor (Sensor 1) side)	AFHT B1	No. 2
	AFTHB2 *
	IG (LAF O2)	No. 3
	VCENTB1	No. 4
	VCENTB2 *
	IPB1	No. 5
	IPB2 *
	VSB1	No. 6
	VSB2 *

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

Is there continuity to body ground at any terminal?

YES

Replace the A/F sensor (Sensor 1) .

Go to step 6.

A/F sensor (Sensor 1) internal circuit check 2

-1. Check for continuity between the following test points and the A/F sensor (Sensor 1) 6P connector No. 3 individually.

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit board: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected

Connector	Test circuit	Terminal
A/F sensor (Sensor 1) (A/F sensor (Sensor 1) side)	VCENTB1	No. 4
	VCENTB2 *
	IPB1	No. 5
	IPB2 *
	VSB1	No. 6
	VSB2 *

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

Is there continuity?

YES

Replace the A/F sensor (Sensor 1) .

Go to step 7.

Shorted wire check (AFHT B1 (AFTHB2) * line):

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

- 2. Disconnect the following connector.

PCM connector C (51P)

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

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit board: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
	PCM connector C (51P): disconnected
Test point 1	PCM connector C (51P) No. 6 - Refer to: PCM Connector for Inputs and Outputs (6-Speed A/T) (2016 2017 2018 2019 2020), or PCM Connector for Inputs and Outputs (9-Speed A/T) (2016 2017 2018)
	PCM connector C (51P) No. 8 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2016 2017 2018), or PCM Connector for Inputs and Outputs (6-Speed A/T) (2016 2017 2018 2019 2020) *
Test point 2	Body ground

Is there continuity?

YES

Repair a short in the AFHT B1 (AFTHB2) * wire between the PCM (C6 (C8) *) and the A/F sensor (Sensor 1).

The AFHT B1 (AFTHB2) * wire is not shorted. Go to step 8.

Open wire check (AFHT B1 (AFTHB2) * line):

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

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit board: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
	PCM connector C (51P): disconnected
Test point 1	Rear A/F sensor (Bank 1, Sensor 1) 6P connector No. 2
	Front A/F sensor (Bank 2, Sensor 1) 6P connector No. 2 *

Test point 2	PCM connector C (51P) No. 6 - Refer to: PCM Connector for Inputs and Outputs (6-Speed A/T) (2016 2017 2018 2019 2020), or PCM Connector for Inputs and Outputs (9-Speed A/T) (2016 2017 2018)
	PCM connector C (51P) No. 8 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2016 2017 2018), or PCM Connector for Inputs and Outputs (6-Speed A/T) (2016 2017 2018 2019 2020) *

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

Is there continuity?

YES

The AFHT B1 (AFTHB2) * wire is OK. Go to step 9.

Repair an open in the AFHT B1 (AFTHB2) * wire between the PCM (C6 (C8) *) and the A/F sensor (Sensor 1).

Open wire check (IG (LAF O2)/FI SUB line)

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

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit board: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
	PCM connector C (51P): disconnected
Test point 1	Relay circuit board connector A (10P) No. 4
Test point 2	A/F sensor (Sensor 1) 6P connector No. 3

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

Is there continuity?

YES

The IG (LAF O2)/FI SUB wire is OK. Go to step 10.

Repair an open in the IG (LAF O2)/FI SUB wire between the A/F sensor (Sensor 1) and the relay circuit board.

Open wire check (LAF RLY line)

-1. Disconnect the following connector.

PCM connector A (51P)

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

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit board: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
	PCM connector A (51P): disconnected
Test point 1	Relay circuit board connector A (10P) No. 6
Test point 2	PCM connector A (51P) No. 14 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2016 2017 2018), or PCM Connector for Inputs and Outputs (6-Speed A/T) (2016 2017 2018 2019 2020)

Is there continuity?

YES

The LAF RLY 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 (6-Speed A/T), (9-Speed A/T 2016 2017 2018), .

Repair an open in the LAF RLY wire between the PCM (A14) and the relay circuit board.

Shorted wire check (IG (LAF O2)/FI SUB line)

-1. Disconnect the following connectors.

Relay circuit board connector A (10P)

Front and rear A/F sensor (Sensor 1) 6P connectors

Front and rear secondary HO2S (Sensor 2) 4P connectors

EVAP canister vent shut valve 2P connector (USA and Canada models)

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

Test condition	Vehicle OFF (LOCK) mode
	Relay circuit A (10P): disconnected
	Front and rear A/F sensor (Sensor 1) 6P connectors: disconnected
	Front and rear secondary HO2S (Sensor 2) 4P connectors: disconnected
	EVAP canister vent shut valve 2P connector (USA and Canada models): disconnected
Test point 1	A/F sensor (Sensor 1) 6P connector No. 3
Test point 2	Body ground

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

Is there continuity?

YES

Repair a short in the IG (LAF O2)/FI SUB wire between the relay circuit board, the A/F sensor (Sensor 1), secondary HO2S (Sensor 2), and the EVAP canister vent shut valve (USA and Canada models). Also replace the No. A22 (15 A) fuse in the under-hood fuse/relay box.

The IG (LAF O2)/FI SUB wire is OK. Check the under-hood fuse/relay box, and replace it if needed . Also replace the No. A22 (15 A) fuse in the under-hood fuse/relay box.