DTC P0137 / P0138 / P0140

DTC Detecting Condition and Trouble Area

DTC detecting condition	Trouble area
P0137: O2 Sensor Circuit Low Voltage (Sensor 2) Output voltage of HO2S-2 circuit is lower than 0.06 V for 30 sec. after warming up. (3 D/C detection logic)	•HO2S-2 and/or its circuit •HO2S-2 heater and/or its circuit •Exhaust system •Air intake system •Fuel system •ECM
P0138: O2 Sensor Circuit High Voltage (Sensor 2) Output voltage of HO2S-2 signal circuit is higher than 1.25 V for 25 sec. (3 D/C detection logic)
P0140: O2 Sensor Circuit No Activity Detected (Sensor 2) Output voltage of HO2S-2 circuit stays between 0.42 to 0.50 V for 25 sec. (3 D/C detection logic)

Circuit Diagram

[A]:	ECM connector (View: [a])	B1:	HO2S-2 heater power supply circuit	2.	HO2S-2
A1:	HO2S-1 heater power supply circuit	B2:	HO2S-2 signal circuit	3.	ECM
A2:	HO2S-1 signal circuit	B3:	HO2S-2 ground circuit	4.	Shield wire
A3:	HO2S-1 ground circuit	B4:	HO2S-2 heater drive circuit
A4:	HO2S-1 heater drive circuit	1.	HO2S-1

DTC Confirmation Procedure

P0137

WARNING:

If you do not select a suitable route and take proper precautions when performing a road test, an accident can occur.

•Select a level road with no traffic to minimize the risk of accident.
•Perform the test extremely carefully.
•Perform the road test with 2 persons, a driver and a tester.

NOTE:

•Check that the following conditions are met in this “DTC Confirmation Procedure”.

—Battery voltage ≥ 11 V
—A/F feedback (closed loop) control is activated.

•Check that the following DTCs are not detected in this “DTC Confirmation Procedure”.

—HO2S-2 heater (P0036, P0037 and P0038)
—ECT sensor (P0116, P0117 and P0118)

1)Warm up engine to normal operating temperature.

2)Drive vehicle at 50 to 80 km/h (31 to 50 mile/h) constantly for 10 min. or more.

P0138 / P0140

WARNING:

If you do not select a suitable route and take proper precautions when performing a road test, an accident can occur.

•Select a level road with no traffic to minimize the risk of accident.
•Perform the test extremely carefully.
•Perform the road test with 2 persons, a driver and a tester.

NOTE:

•Check that the following condition is met in this “DTC Confirmation Procedure”.

—Battery voltage > 11 V

•Check that the following DTCs are not detected in this “DTC Confirmation Procedure”.

—HO2S-2 heater (P0036, P0037 and P0038)

1)Warm up engine to normal operating temperature.

2)Drive vehicle at 50 to 80 km/h (31 to 50 mile/h) constantly for 10 min. or more.

DTC Troubleshooting

Step	Action	Yes	No
1	Was “Engine and Emission Control System Check” performed?	Go to Step 2.	Go to Engine and Emission Control System Check:M16A.
2	DTC check Is there any DTC(s) other than P0137, P0138 and P0140?	Go to troubleshooting for applicable DTC(s).	Go to Step 3.
3	HO2S-2 signal circuit and ground circuit check 1)With ignition “OFF”, disconnect “C01” and “E01” connectors of ECM and HO2S-2 connector. 2)Check for proper terminal connection to “C01” and “E01” connectors and HO2S-2 connector. 3)If connections are OK, check the following points. •Resistance of “B2” and “B3” circuits: less than 1 Ω •Resistance between each of “B2” and “B3” circuits and ground: infinity •Resistance between “B2” circuit terminal and other terminal at HO2S-2 connector: infinity •Resistance between “B3” circuit terminal and other terminal at HO2S-2 connector: infinity •Voltage of “B2” and “B3” circuits: approx. 0 V (When ignition is “ON”) Is check result OK?	Go to Step 4.	Repair or replace defective wiring harness.
4	Exhaust system and air intake system check 1)Check exhaust system and air intake system for clogging or leakage. Is check result OK?	Go to Step 5.	Repair or replace defective part.
5	HO2S-2 heater circuit check 1)Check HO2S-2 heater circuits according to Step 2 – 3 under DTC P0036 / P0037 / P0038:M16A. Is check result OK?	Go to Step 6.	Repair or replace defective wiring harness.
6	Fuel injector and its circuit check 1)Check fuel injector circuit. 2)Check fuel injectors. Is check result OK?	Go to Step 7.	Faulty injector(s) or its circuit.
7	DTC recheck 1)Replace HO2S-2. 2)Perform “DTC Confirmation Procedure” to check for DTCs. Is DTC P0137, P0138 or P0140 still detected?	Replace ECM and recheck DTC.	End.