DTC Troubleshooting: P0141

DTC P0141: Secondary HO2S (Sensor 2) Heater Circuit Malfunction

NOTE: Before you troubleshoot, review the general troubleshooting information.

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P0141 Secondary HO2S (Sensor 2) Heater Circuit Malfunction

Problem verification:

Problem verification

?1.	Turn the vehicle to the ON mode.

?2.	Clear the DTC with the HDS.

?3.	Start the engine, and let it idle.

?4.

Check for Pending or Confirmed DTCs with the HDS.

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P0141 Secondary HO2S (Sensor 2) Heater Circuit Malfunction

Is DTC P0141 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 secondary HO2S (Sensor 2) 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.?

Shorted wire check (IG1 ACG/IG1(SO2) line):

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

?2.

Check the following fuse.

Fuse	No. C30 (10 A)
Location	Under-dash fuse/relay box

Is the fuse OK?


	YES

The IG1 ACG/IG1(SO2) wire is not shorted. Go to step 3.


	NO

Repair a short in the IG1 ACG/IG1(SO2) wire between the secondary HO2S (Sensor 2) and the No. C30 (10 A) fuse. Also replace the No. C30 (10 A) fuse.?

Secondary HO2S (Sensor 2) internal heater resistance check:

Secondary HO2S (Sensor 2) internal heater resistance check

?1.

Disconnect the following connector.

Secondary HO2S (Sensor 2) 4P connector

?2.

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

Test condition	Vehicle OFF (LOCK) mode
	Secondary HO2S (Sensor 2) 4P connectors: disconnected
Test point 1	Secondary HO2S (Sensor 2) 4P connector No. 3 (secondary HO2S (Sensor 2) side)
Test point 2	Secondary HO2S (Sensor 2) 4P connector No. 4 (secondary HO2S (Sensor 2) side)

Is there 5.4?7.3 ? at room temperature?


	YES

Go to step 4.


	NO

Replace secondary HO2S (Sensor 2).?

Secondary HO2S (Sensor 2) internal circuit check:

Secondary HO2S (Sensor 2) internal circuit check

?1.

At the sensor side, check for continuity between test point 1 and 2

Test condition	Vehicle OFF (LOCK) mode
	Secondary HO2S (Sensor 2) 4P connectors: disconnected
Test point 1	Secondary HO2S (Sensor 2) 4P connector No. 3 and No. 4 (secondary HO2S (Sensor 2) side)
Test point 2	Body ground

Is there continuity?


	YES

Replace secondary HO2S (Sensor 2).?


	NO

Go to step 5.

Shorted wire check (SO2HT line):

Shorted wire check (SO2HT line)

?1.	Jump the SCS line with the HDS.

?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
	Secondary HO2S (Sensor 2) 4P connector: disconnected
	PCM connector C (51P): disconnected
Test point 1	PCM connector C (51P) No. 9
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the SO2HT wire between the PCM (C9) and secondary HO2S (Sensor 2).?


	NO

The SO2HT wire is not shorted. Go to step 6.

Open wire check (SO2HT line):

Open wire check (SO2HT line)

?1.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	Secondary HO2S (Sensor 2) 4P connector: disconnected
	PCM connector C (51P): disconnected
Test point 1	Secondary HO2S (Sensor 2) 4P connector No. 3
Test point 2	PCM connector C (51P) No. 9

Is there continuity?


	YES

The SO2HT wire is OK. Go to step 7.


	NO

Repair an open in the SO2HT wire between the PCM (C9) and secondary HO2S (Sensor 2).?

Open wire check (IG1 ACG/IG1(SO2) line):

Open wire check (IG1 ACG/IG1(SO2) line)

?1.	Turn the vehicle to the ON mode.

?2.

Measure the voltage between test points 1 and 2.

Test condition	Vehicle ON mode
	Secondary HO2S (Sensor 2) 4P connector: disconnected
	PCM connector C (51P): disconnected
Test point 1	Secondary HO2S (Sensor 2) 4P connector No. 4
Test point 2	Body ground

Is there battery voltage?


	YES

The IG1 ACG/IG1(SO2) is not open. Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If DTC P0141 goes away and the PCM was updated, troubleshooting is complete. If DTC P0141 goes away and the PCM was substituted, replace the original PCM.?


	NO

Repair an open in the IG1 ACG/IG1(SO2) wire between secondary HO2S (Sensor 2) and the No. C30 (10 A) fuse in the under-dash fuse/relay box.?