DTC Troubleshooting: P0135 (K20C2) - Honda Civic FC/FK 2016-2021

1.

Problem verification:

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
P0135 A/F Sensor (Sensor 1) Heater Circuit Malfunction

Is DTC P0135 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.?

2.

DTC check:

DTC check

?1.

Check for Pending or Confirmed DTCs with the HDS.

DTC Description	Confirmed DTC	Pending DTC
P1658 ETCS Control Relay ON Malfunction
P1659 ETCS Control Relay OFF Malfunction

Is DTC P1658 and/or P1659 indicated?


	YES

Go to the indicated DTC's troubleshooting.?


	NO

Go to step 3.

3.

Fuse check:

Fuse check

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

?2.

Check the following fuse.

Fuse	No. A11 (5 A)
Location	Under-hood fuse/relay box

Is the fuse OK?


	YES

Go to step 4.


	NO

Go to step 10.

4.

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

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
	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)

Is there 2.8?4.5 ? at room temperature?


	YES

Go to step 5.


	NO

Replace the A/F sensor (Sensor 1).?

5.

A/F sensor (Sensor 1) internal circuit check 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
	A/F sensor (Sensor 1) 6P connector: disconnected

Connector	Test circuit	Terminal
A/F sensor (Sensor 1) (A/F sensor (Sensor 1) side)	AFHT	No. 2
	IGPS(LAF+)	No. 3
	VCENT	No. 4
	IP	No. 5
	VS	No. 6

Is there continuity?


	YES

Replace the A/F sensor (Sensor 1).?


	NO

Go to step 6.

6.

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

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
	A/F sensor (Sensor 1) 6P connector: disconnected

Connector	Test circuit	Terminal
A/F sensor (Sensor 1) (A/F sensor (Sensor 1) side)	VCENT	No. 4
	IP	No. 5
	VS	No. 6

Is there continuity?


	YES

Replace the A/F sensor (Sensor 1).?


	NO

Go to step 7.

7.

Shorted wire check (AFHT line):

Shorted wire check (AFHT 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. 13
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the AFHT wire between the PCM (E13) and the A/F sensor (Sensor 1).?


	NO

The AFHT wire is not shorted. Go to step 8.

8.

Open wire check (AFHT line):

Open wire check (AFHT 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	A/F sensor (Sensor 1) 6P connector No. 2
Test point 2	PCM connector E (80P) No. 13

Is there continuity?


	YES

The AFHT wire is OK. Go to step 9.


	NO

Repair an open in the AFHT wire between the PCM (E13) and the A/F sensor (Sensor 1).?

9.

Open wire check (IGPS(LAF+)/IGPS(LAF) line):

Open wire check (IGPS(LAF+)/IGPS(LAF) line)

?1.	Turn the vehicle to the ON mode.

?2.

Measure the voltage between test points 1 and 2.

Test condition	Vehicle ON mode
	A/F sensor (Sensor 1) 6P connector: disconnected
	PCM connector E (80P): disconnected
Test point 1	A/F sensor (Sensor 1) 6P connector No. 3
Test point 2	Body ground

Is there battery voltage?


	YES

The IGPS(LAF+)/IGPS(LAF) 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. If DTC P0135 goes away and the PCM was substituted, replace the original PCM.?


	NO

Repair an open in the IGPS(LAF+)/IGPS(LAF) wire between the No. A11 (5 A) fuse in the under-hood fuse/relay box and the A/F sensor (Sensor 1).?

10.

Shorted wire check (IGPS(LAF+)/IGPS(LAF) line):

Shorted wire check (IGPS(LAF+)/IGPS(LAF) line)

?1.	Remove the blown No. A11 (5 A) fuse from the under-hood fuse/relay box.

?2.

Disconnect the following connectors.

A/F sensor (Sensor 1) 6P connector

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

?3.

Check for continuity between test points 1 and 2.

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

Is there continuity?


	YES

Repair a short in the IGPS(LAF+)/IGPS(LAF) wire between the No. A11 (5 A) fuse and the A/F sensor (Sensor 1), or between the No. A11 (5 A) fuse and the EVAP canister vent shut valve. Also replace the No. A11 (5 A) fuse.?


	NO

The IGPS(LAF+)/IGPS(LAF) wire is OK. Replace the No. A11 (5 A) fuse, then recheck. If the fuse is blown again, replace the under-hood fuse/relay box.?