DTC P0135, P0155 (19-21 9-Speed A/T)

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

DTC P0155  : Front Air Fuel Ratio (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 (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. Check for Pending or Confirmed DTCs with the HDS.

   DTC Description	Confirmed DTC	Pending DTC
   P0135 Rear Air Fuel Ratio (A/F) Sensor (Bank 1, Sensor 1) Heater Circuit Malfunction
   P0155 Front Air Fuel Ratio (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.

   NO 

   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 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

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

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

   - 2. Disconnect the following connector.

   A/F sensor (Sensor 1) 6P connector

   - 3. At the A/F sensor (Sensor 1) side, measure the resistance between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	A/F sensor (Sensor 1) 6P connector: disconnected
   Test point 1	Rear A/F sensor (Bank 1, Sensor 1) 6P connector (male terminals) No. 2 (sensor side):
   	Front A/F sensor (Bank 2, Sensor 1) 6P connector (male terminals) No. 2 (sensor side):
   Test point 2	Rear A/F sensor (Bank 1, Sensor 1) 6P connector (male terminals) No. 3 (sensor side):
   	Front A/F sensor (Bank 2, Sensor 1) 6P connector (male terminals) No. 3 (sensor side):

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

   Is there 2.8-4.5 Ω at room temperature?

   YES 

   Go to step 3.

   NO 

   Replace the A/F sensor (Sensor 1) .

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

   -1. At the A/F sensor (Sensor 1) side, check for continuity between the following test points and body ground individually.

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

   Connector	Test circuit	Terminal
   Rear A/F sensor (Bank 1, Sensor 1) 6P connector (male terminals) (sensor side): (Front A/F sensor (Bank 2, Sensor 1) 6P connector (male terminals) (sensor side)) *:	AFHT B1 (AFTHB2) *	No. 2
   	IG (LAF O2)	No. 3
   	VCENTB1 (VCENTB2) *	No. 4
   	IPB1 (IPB2) *	No. 5
   	VSB1 (VSB2) *	No. 6

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

   Is there continuity to body ground at any terminal?

   YES 

   Replace the A/F sensor (Sensor 1) .

   NO 

   Go to step 4.

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

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

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

   Connector	Test circuit	Terminal
   Rear A/F sensor (Bank 1, Sensor 1) 6P connector (male terminals) (sensor side): (Front A/F sensor (Bank 2, Sensor 1) 6P connector (male terminals) (sensor side)) *:	VCENTB1 (VCENTB2) *	No. 4
   	IPB1 (IPB2) *	No. 5
   	VSB1 (VSB2) *	No. 6

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

   Is there continuity?

   YES 

   Replace the A/F sensor (Sensor 1) .

   NO 

   Go to step 5.

5. 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 E (80P)

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

   Test condition	Vehicle OFF (LOCK) mode
   	A/F sensor (Sensor 1) 6P connector: disconnected
   	PCM connector E (80P): disconnected
   Test point 1	PCM connector E (80P) No. 9 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2019 2020 2021),
   	PCM connector E (80P) No. 10 * - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2019 2020 2021), or
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short in the AFHT B1 (AFTHB2) * wire between the PCM (E9 (E10) *) and the A/F sensor (Sensor 1).

   NO 

   The AFHT B1 (AFTHB2) * wire is not shorted. Go to step 6.

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

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

   Test condition	Vehicle OFF (LOCK) mode
   	A/F sensor (Sensor 1) 6P connector: disconnected
   	PCM connector E (80P): disconnected
   Test point 1	Rear A/F sensor (Bank 1, Sensor 1) 6P connector (female terminals) No. 2:
   	Front A/F sensor (Bank 2, Sensor 1) 6P connector (female terminals) No. 2 *:
   Test point 2	PCM connector E (80P) No. 9 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2019 2020 2021)
   	PCM connector E (80P) No. 10 * - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2019 2020 2021)

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

   Is there continuity?

   YES 

   The AFHT B1 (AFTHB2) * wire is OK. Go to step 7.

   NO 

   Repair an open in the AFHT B1 (AFTHB2) * wire between the PCM (E9 (E10) *) and the A/F sensor (Sensor 1).

7. 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

   - 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
   	PCM connector E (80P): disconnected
   Test point 1	Rear A/F sensor (Bank 1, Sensor 1) 6P connector (female terminals) No. 3:
   	Front A/F sensor (Bank 2, Sensor 1) 6P connector (female terminals) 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). Also replace the No. A22 fuse. - Refer to: Fuse to Components Index (Without Auto Idle Stop System) (2019 2020 2021) or Fuse to Components Index (With Auto Idle Stop System) (2019 2020 2021)

   NO 

   The IG (LAF O2)/FI SUB) wire is not shorted. Go to step 8.

8. 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 E (80P): disconnected
   Test point 1	Relay circuit board connector A (10P) No. 4
   Test point 2	Rear A/F sensor (Bank 1, Sensor 1) 6P connector (female terminals) No. 3:
   	Front A/F sensor (Bank 2, Sensor 1) 6P connector (female terminals) 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 9.

   NO 

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

9. Open wire check (LAF RLY line)

   -1. Disconnect the following connector.

   PCM connector A (50)

   - 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 (50P): disconnected
   	PCM connector E (80P): disconnected
   Test point 1	Relay circuit board connector A (10P) No. 6
   Test point 2	PCM connector A (50P) No. 49 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2019 2020 2021) .

   Is there continuity?

   YES 

   The LAF RLY wire is OK. Go to step10

   NO 

   Repair an open in the LAF RLY wire between the PCM (A49) and the relay circuit board.

10. Fuse check

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

    - 2. Check the following fuse.

    Fuse	No. A22 - Refer to: Fuse to Components Index (Without Auto Idle Stop System) (2019 2020 2021) or Fuse to Components Index (With Auto Idle Stop System) (2019 2020 2021)

    Is the fuse OK?

    YES 

    Go to step 11.

    NO 

    Repair a short in the +B FI SUB wire between the No. A22 fuse and the under-hood fuse/relay box. Also replace the No. A22 fuse.

11. Open wire check (+B FI SUB line)

    -1. Measure the voltage between test points 1 and 2.

    Test condition	Vehicle OFF (LOCK) mode
    	A/F sensor (Sensor 1) 6P connector: disconnected
    	PCM connector E (80P): disconnected
    	PCM connector A (50P): disconnected
    	Relay circuit board: disconnected
    Test point 1	Relay circuit board connector A (10P) No. 2
    Test point 2	Body ground

    Is there battery voltage?

    YES 

    The +B FI SUB wire is OK. Go to step 12.

    NO 

    Repair an open in the +B FI SUB wire between the No. A22 - Refer to: Fuse to Components Index (Without Auto Idle Stop System) (2019 2020 2021) or Fuse to Components Index (With Auto Idle Stop System) (2019 2020 2021)

12. Relay circuit board check

    -1. Remove and test the relay circuit board.

    Is the relay circuit board OK?

    YES 

    The relay circuit board 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 P0135 and/or P0155* goes away and the PCM was substituted, replace the original PCM - Refer to: PCM Removal and Installation (9-Speed A/T 2019 2020 2021) .

    NO 

    Replace the relay circuit board .