DTC Troubleshooting: P0137

DTC P0137: Secondary HO2S (Sensor 2) Circuit Low Voltage

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

DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
P0137 Secondary HO2S (Sensor 2) Circuit Low Voltage

Problem verification:

Problem verification

?1.	Turn the vehicle to the ON mode.

?2.	Clear the DTC with the HDS.

?3.	Start the engine.

?4.	Hold the engine speed at 3,000 rpm without load (CVT in P or N, M/T in neutral) until the radiator fan comes on.

?5.

Monitor the OBD STATUS for DTC P0137 in the DTCs MENU with the HDS.

DTC Description	OBD STATUS
P0137 Secondary HO2S (Sensor 2) Circuit Low Voltage

Does the HDS indicate FAILED?


	YES

The failure is duplicated. Go to step 2.


	NO

If the HDS indicates PASSED, 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. If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 1-4 and recheck.?

Determine possible failure area (secondary HO2S (Sensor 2), others):

Determine possible failure area (secondary HO2S (Sensor 2), others)

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

?2.

Disconnect the following connector.

Secondary HO2S (Sensor 2) 4P connector

?3.

Connect terminals A and B with a jumper wire.

Terminal A	Secondary HO2S (Sensor 2) 4P connector No. 1
Terminal B	Secondary HO2S (Sensor 2) 4P connector No. 2

?4.	Turn the vehicle to the ON mode.

?5.

Check the parameter(s) below with the HDS.

Signal	Threshold		Current conditions
Signal	Values	Unit	Values	Unit
HO2S S2	Less than 0.12	V

Do the current condition(s) match the threshold?


	YES

Go to step 3.


	NO

Replace secondary HO2S (Sensor 2).?

Determine possible failure area (short in SO2 line, short in SO2SG line):

Determine possible failure area (short in SO2 line, short in SO2SG line)

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

?2.	Remove the jumper wire from the secondary HO2S (Sensor 2) 4P connector.

?3.	Turn the vehicle to the ON mode.

?4.

Check the parameter(s) below with the HDS.

Signal	Threshold		Current conditions
Signal	Values	Unit	Values	Unit
HO2S S2	about 5.0	V

Do the current condition(s) match the threshold?


	YES

Go to step 4.


	NO

Go to step 5.

Shorted wire check (SO2SG line):

Shorted wire check (SO2SG line)

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

?2.	Jump the SCS line with the HDS.

?3.

Disconnect the following connector.

PCM connector C (51P)

?4.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector C (51P): disconnected
	Secondary HO2S (Sensor 2) 4P connector: disconnected
Test point 1	PCM connector C (51P) No. 39
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the SO2SG wire between the PCM (C39) and secondary HO2S (Sensor 2).?


	NO

The SO2SG wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If DTC P0137 goes away and the PCM was updated, troubleshooting is complete. If DTC P0137 goes away and the PCM was substituted, replace the original PCM.?

Shorted wire check (SO2 line):

Shorted wire check (SO2 line)

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

?2.	Jump the SCS line with the HDS.

?3.

Disconnect the following connector.

PCM connector C (51P)

?4.

Check for continuity between test points 1 and 2.

Test condition	Vehicle OFF (LOCK) mode
	PCM connector C (51P): disconnected
	Secondary HO2S (Sensor 2) 4P connector: disconnected
Test point 1	PCM connector C (51P) No. 38
Test point 2	Body ground

Is there continuity?


	YES

Repair a short in the SO2 wire between the PCM (C38) and secondary HO2S (Sensor 2).?


	NO

The SO2 wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If DTC P0137 goes away and the PCM was updated, troubleshooting is complete. If DTC P0137 goes away and the PCM was substituted, replace the original PCM.?