DTC P0135, P0155

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 A/T System (2014 2015), or How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the Brake Booster Pressure Monitoring System (2016 2017 2018 2019 2020), or How to Troubleshoot the Fuel and Emissions Systems(With Auto Idle Stop System) (2016) .
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 PGM-FI subrelay, 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.

Fuse check

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

- 2. Check the following fuse.

Fuse	No. C8 (15 A)
Location	Under-hood fuse/relay box

Is the fuse OK?

YES

Go to step 3.

Go to step 11.

Relay check
-1. Remove the PGM-FI subrelay (A) from the under-hood fuse/relay box.

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- 2. Test the PGM-FI subrelay.

Is the relay OK?

YES

Go to step 4.

NO

Replace the PGM-FI subrelay.

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
	PGM-FI subrelay: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
Test circuit	AFHT B1 (AFHT B2) *, IG(LAF O2)
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)

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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 internal circuit check 1

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

Test condition	Vehicle OFF (LOCK) mode
	PGM-FI subrelay: 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
	AFHT B2 *	No. 2
	IG(LAF O2)	No. 3
	VCENTB1	No. 4
	VCENTB2 *	No. 4
	IPB1	No. 5
	IPB2 *	No. 5
	VSB1	No. 6
	VSB2 *	No. 6

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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

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

Test condition	Vehicle OFF (LOCK) mode
	PGM-FI subrelay: 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 *

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Is there continuity?

YES

Replace the A/F sensor (Sensor 1) .

Go to step 7.

Shorted wire check (AFHT B1 (AFHT B2) * line):

- 1.Jump the SCS line with the HDS.

- 2. Disconnect the following connector.

PCM connector C (51P) - Refer to: How to Troubleshoot the A/T System (2014 2015), or How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the Brake Booster Pressure Monitoring System (2016 2017 2018 2019 2020), or How to Troubleshoot the Fuel and Emissions Systems(With Auto Idle Stop System) (2016)

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

Test condition	Vehicle OFF (LOCK) mode
	PGM-FI subrelay: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
	PCM connector C (51P): disconnected
Test circuit	AFHT B1 (AFHT B2) *
Test point 1	PCM connector C (51P) No. 6 (TAN)
	PCM connector C (51P) No. 8 (GRY) *
Test point 2	Body ground

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Is there continuity?

YES

Repair a short in the AFHT B1 (AFHT B2) * wire between the PCM (C6 (C8) *) and the A/F sensor (Sensor 1).

The AFHT B1 (AFHT B2) * wire is not shorted. Go to step 8.

Open wire check (AFHT B1 (AFHT B2) * line):

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

Test condition	Vehicle OFF (LOCK) mode
	PGM-FI subrelay: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
	PCM connector C (51P): disconnected
Test circuit	AFHT B1 (AFHT B2) *
Test point 1	Rear A/F sensor (Bank 1, Sensor 1) 6P connector No. 2 (TAN)
	Front A/F sensor (Bank 2, Sensor 1) 6P connector No. 2 (GRY) *
Test point 2	PCM connector C (51P) No. 6 (TAN)
	PCM connector C (51P) No. 8 (GRY) *

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Is there continuity?

YES

The AFHT B1 (AFHT B2) * wire is OK. Go to step 9.

Repair an open in the AFHT B1 (AFHT B2) * 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
	PGM-FI subrelay: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
	PCM connector C (51P): disconnected
Test circuit	IG(LAF O2)/FI SUB
Test point 1	A/F sensor (Sensor 1) 6P connector No. 3 (PNK)
Test point 2	PGM-FI subrelay 4P socket No. 2

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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 PGM-FI subrelay.

Open wire check (LAF RLY line)

-1. Disconnect the following connector.

PCM connector A (51P) - Refer to: How to Troubleshoot the Brake Booster Pressure Monitoring System (2016 2017 2018 2019 2020), or How to Troubleshoot the Fuel and Emissions Systems(With Auto Idle Stop System) (2016), or How to Troubleshoot the A/T System (2014 2015), or How to Troubleshoot the Fuel and Emissions Systems

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

Test condition	Vehicle OFF (LOCK) mode
	PGM-FI subrelay: disconnected
	A/F sensor (Sensor 1) 6P connector: disconnected
	PCM connector A (51P): disconnected
Test circuit	LAF RLY
Test point 1	PGM-FI subrelay 4P socket No. 4
Test point 2	PCM connector A (51P) No. 14 (PNK)

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Is there continuity?

YES

The LAF RLY wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM - Refer to: PCM Removal and Installation (2014 2015), or PCM Removal and Installation (2016) .

Repair an open in the LAF RLY wire between the PCM (A14) and the PGM-FI subrelay.

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

-1. Remove the PGM-FI subrelay (A) and the No. C28 (7.5 A) fuse from the under-hood fuse/relay box.

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- 2. Jump the SCS line with the HDS.

- 3. Disconnect the following connectors.

PCM connector A (51P) - Refer to: How to Troubleshoot the Fuel and Emissions Systems, or How to Troubleshoot the A/T System (2014 2015), or How to Troubleshoot the Brake Booster Pressure Monitoring System (2016 2017 2018 2019 2020), or How to Troubleshoot the Fuel and Emissions Systems(With Auto Idle Stop System) (2016)

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

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

Test condition	Vehicle OFF (LOCK) mode
	PGM-FI subrelay: disconnected
	No. C8 (15 A) fuse: disconnected
	PCM connector A (51P): disconnected
	Front and rear secondary HO2S (Sensor 2) 4P connectors: disconnected
	Front and rear A/F sensor (Sensor 1) 6P connectors: disconnected
	EVAP canister vent shut valve 2P connector: disconnected
Test circuit	IG(LAF O2)/FI SUB
Test point 1	A/F sensor (Sensor 1) 6P connector No. 3 (PNK)
Test point 2	Body ground

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Is there continuity?

YES

Repair a short in the IG(LAF O2)/FI SUB wire between the PGM-FI subrelay, secondary HO2S (Sensor 2), the A/F sensor (Sensor 1), the EVAP canister vent shut valve, and the PCM. Also replace the No. C8 (15 A) fuse.

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. C8 (15 A) fuse.