DTC Code | DTC Name |
---|---|
P0136 | Oxygen Sensor Circuit (Bank 1 Sensor 2) |
P0137 | Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2) |
P0138 | Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2) |
DESCRIPTION
In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC (Three-Way Catalytic Converter) is used. For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel level. For the purpose of helping the ECM to deliver accurate air fuel ratio control, a heated oxygen sensor is used.
The heated oxygen sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).
When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas is high. The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is lean (low voltage, i.e. less than 0.45 V).
Conversely, when the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas is low. The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is rich (high voltage, i.e. higher than 0.45 V). The heated oxygen sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric level.
The ECM uses the supplementary information from the heated oxygen sensor to determine whether the air fuel ratio after the TWC is rich or lean, and adjusts the fuel injection duration accordingly. Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control.
DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory |
---|---|---|---|---|---|
P0136 | Oxygen Sensor Circuit (Bank 1 Sensor 2) | Abnormal voltage output: During active air fuel ratio control, the following conditions (a) and (b) are met for a certain period of time (2 trip detection logic)
|
|
Comes on (Euro-OBD) / - (Except Euro-OBD) | DTC stored (Euro-OBD) / - (Except Euro-OBD) |
P0137 | Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2) | Low voltage (open): During active air fuel ratio control, the following conditions (a) and (b) are met for a certain period of time (2 trip detection logic)
|
|
Comes on | DTC stored |
P0138 | Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2) | High voltage (short): During active air fuel ratio control, the following conditions (a) and (b) are met for a certain period of time (2 trip detection logic)
|
|
Comes on (Euro-OBD) / - (Except Euro-OBD) | DTC stored (Euro-OBD) / - (Except Euro-OBD) |
MONITOR DESCRIPTION
The ECM usually performs air fuel ratio feedback control so that the air fuel ratio sensor output indicates a near stoichiometric air fuel level. This vehicle includes active air fuel ratio control in addition to regular air fuel ratio control. The ECM performs active air fuel ratio control to detect any deterioration in the Three-Way Catalytic Converter (TWC) and heated oxygen sensor malfunctions (refer to the diagram below).
Active air fuel ratio control is performed for approximately 30 seconds while driving with a warm engine. During active air fuel ratio control, the air fuel ratio is forcibly regulated to become lean or rich by the ECM. If the ECM detects a malfunction, a DTC is stored.
While the ECM is performing active air fuel ratio control, the air fuel ratio is forcibly regulated to become rich or lean. If the sensor is not functioning properly, the voltage output variation is small. For example, when the heated oxygen sensor voltage does not decrease to less than 0.21 V and does not increase to 0.69 V or higher during active air fuel ratio control, the ECM determines that the sensor voltage output is abnormal and stores DTC P0136.
During active air fuel ratio control, the ECM calculates the Oxygen Storage Capacity (OSC)* of the Three-Way Catalytic Converter (TWC) by forcibly regulating the air fuel ratio to become rich or lean.
If the heated oxygen sensor has an open or short circuit, or the voltage output of the sensor noticeably decreases, the OSC indicates an extremely high value. Even if the ECM attempts to continue regulating the air fuel ratio to become rich or lean, the heated oxygen sensor output does not change.
While performing active air fuel ratio control, when the target air fuel ratio is rich and the heated oxygen sensor voltage output is less than 0.21 V (lean), the ECM interprets this as an abnormally low sensor output voltage and stores DTC P0137. When the target air fuel ratio is lean and the voltage output is higher than 0.69 V (rich) during active air fuel ratio control, the ECM determines that the sensor voltage output is abnormally high and stores DTC P0138.
*: The TWC has the capability to store oxygen. The OSC and the emission purification capacity of the TWC are mutually related. The ECM determines whether the catalyst has deteriorated, based on the calculated OSC value.
MONITOR STRATEGY
Required Sensors/Components (Main) | Heated oxygen sensor (sensor 2) |
Required Sensors/Components (Related) | Crankshaft position sensor Engine coolant temperature sensor Mass air flow meter sub-assembly Throttle position sensor Air fuel ratio sensor |
Frequency of Operation | Once per driving cycle |
TYPICAL ENABLING CONDITIONS
Active air fuel ratio control | Executing |
Active air fuel ratio control begins when all of the following conditions met: | - |
Battery voltage | 11 V or higher |
Engine coolant temperature | 75°C (167°F) or higher |
Idling | Off |
Engine speed | Less than 4000 rpm |
Air fuel ratio sensor status | Activated |
Fuel system status | Closed loop |
Engine load | 10% or higher, and less than 90% |
TYPICAL MALFUNCTION THRESHOLDS
Either of the following conditions is met | 1 or 2 |
1. Both of the following conditions are met | - |
(a) Commanded air fuel ratio | 14.4 or less |
(b) Heated oxygen sensor voltage | 0.21 V or higher, and less than 0.69 V |
2. Both of the following conditions are met | - |
(c) Commanded air fuel ratio | 14.8 or more |
(d) Heated oxygen sensor voltage | 0.21 V or higher, and less than 0.69 V |
Both of the following conditions are met | - |
(a) Commanded air fuel ratio | 14.4 or less |
(b) Heated oxygen sensor voltage | Less than 0.21 V |
Both of the following conditions are met | - |
(a) Commanded air fuel ratio | 14.8 or more |
(b) Heated oxygen sensor voltage | Higher than 0.69 V |
CONFIRMATION DRIVING PATTERN
Tech Tips
This confirmation driving pattern is used in the "Perform Confirmation Driving Pattern" procedure of the following diagnostic troubleshooting procedure.
Performing this confirmation driving pattern will activate the heated oxygen sensor monitor (the catalyst monitor is performed simultaneously). This is very useful for verifying the completion of a repair.
Connect the GTS to the DLC3.
Turn the engine switch on (IG) and turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the engine switch off and wait for at least 30 seconds.
Turn the engine switch on (IG) and turn the GTS on [A].
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [B].
With the shift lever in D, drive the vehicle at 60 to 100 km/h (37 to 62 mph) for 10 minutes or more [C].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
Read the pending DTCs.
Tech Tips
If a pending DTC is output, the system is malfunctioning.
If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0136, P0137 or P0138.
Check the DTC judgment result.
GTS Display | Description |
---|---|
NORMAL |
|
ABNORMAL |
|
INCOMPLETE |
|
N/A |
|
Tech Tips
If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform steps [C] and [D] again.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
Tech Tips
Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F Sensor function provided in the Active Test. The Control the Injection Volume for A/F Sensor function can help to determine whether the air fuel ratio sensor, heated oxygen sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the Control the Injection Volume for A/F Sensor operation using the GTS.
Connect the GTS to the DLC3.
Start the engine.
Turn the GTS on.
Warm up the engine and run the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / All Data / AFS Voltage B1S1 and O2S B1S2.
Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the GTS.
Tech Tips
The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
GTS Display (Sensor) | Injection Volume | Status | Voltage |
---|---|---|---|
AFS Voltage B1S1 (Air fuel ratio) |
12.5% | Rich | Below 3.1 V |
-12.5% | Lean | Higher than 3.4 V | |
O2S B1S2 (Heated oxygen) |
12.5% | Rich | Higher than 0.55 V |
-12.5% | Lean | Below 0.4 V |
Note
The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / All Data / AFS Voltage B1S1 and O2S B1S2; and then press the graph button on the Data List view.
Note
Inspect the fuses for circuits related to this system before performing the following procedure.
Tech Tips
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.
Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
READ OUTPUT DTC (DTC P0136, P0137 OR P0138)
Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Read the DTCs.
Result | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
|
Tech Tips
If any DTCs other than P0136, P0137 or P0138 are output, troubleshoot those DTCs first.
B |
GO TO STEP 12 Click here |
C |
PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR) Click here |
D |
GO TO DTC CHART Click here |
A |
READ VALUE USING GTS (O2S B1S2)
Connect the GTS to the DLC3.
Start the engine.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / O2S B1S2.
Tester Display |
---|
O2S B1S2 |
Allow the engine to idle.
Read the heated oxygen sensor output voltage while idling.
Result | ||||||
---|---|---|---|---|---|---|
|
B |
PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR) Click here |
A |
INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)
*a | Component without harness connected (Heated Oxygen Sensor) |
Disconnect the heated oxygen sensor connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | |||||||||
---|---|---|---|---|---|---|---|---|---|
|
Result | |||
---|---|---|---|
|
NG |
REPLACE HEATED OXYGEN SENSOR Click here |
OK |
CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)
Turn the engine switch off and wait for 5 minutes or more.
Disconnect the ECM connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | ||||||
---|---|---|---|---|---|---|
|
Result | |||
---|---|---|---|
|
OK |
REPLACE ECM Click here |
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR (HEATED OXYGEN SENSOR - ECM) |
PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)
Connect the GTS to the DLC3.
Start the engine.
Turn the GTS on.
Warm up the engine.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / All Data / AFS Voltage B1S1 and O2S B1S2.
Active Test Display |
---|
Control the Injection Volume for A/F Sensor |
Data List Display |
---|
AFS Voltage B1S1 |
O2S B1S2 |
Change the fuel injection volume using the GTS, and monitor the voltage output of the air fuel ratio and heated oxygen sensors displayed on the GTS.
Tech Tips
The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
The air fuel ratio sensor is displayed as AFS Voltage B1S1, and the heated oxygen sensor is displayed as O2S B1S2 on the GTS.
The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.
Result | |||||||||
---|---|---|---|---|---|---|---|---|---|
|
Tech Tips
A normal heated oxygen sensor voltage (O2S B1S2) reacts in accordance with increases and decreases in fuel injection volumes. When the air fuel ratio sensor voltage (AFS Voltage B1S1) remains at either less or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.
NG |
GO TO STEP 9 Click here |
OK |
INSPECT AIR FUEL RATIO SENSOR
Tech Tips
This air fuel ratio sensor test is to check the air fuel ratio sensor current during the fuel cut operation. When the sensor is normal, the sensor current will indicate less than 2.2 mA in this test.
Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Clear the DTCs.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.
Drive the vehicle at 60 km/h (37 mph) or more for 10 minutes or more.
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Stop the vehicle.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / AFS Current B1S1.
Tester Display |
---|
AFS Current B1S1 |
Drive the vehicle at 60 km/h (37 mph) or more and release the accelerator pedal for at least 5 seconds without depressing the brake pedal in order to execute fuel-cut control. Perform this 3 times.
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
*a | 60 km/h |
*b | 0 km/h |
*c | 10 minutes or more |
*d | 5 seconds or more |
Read the value of the air fuel ratio sensor current while the fuel-cut operation is performed.
Standard Current |
---|
Less than 2.2 mA |
Tech Tips
To measure the air fuel ratio sensor current precisely, perform the fuel-cut operation as long as possible.
If it is difficult to measure the air fuel ratio sensor current, use the snapshot function of the GTS.
Result | |||
---|---|---|---|
|
OK |
GO TO STEP 15 Click here |
NG |
GO TO STEP 9 Click here |
PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)
Connect the GTS to the DLC3.
Start the engine.
Turn the GTS on.
Warm up the engine.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / All Data / O2S B1S2.
Active Test Display |
---|
Control the Injection Volume for A/F Sensor |
Data List Display |
---|
O2S B1S2 |
Change the fuel injection volume using the GTS, and monitor the voltage output of the heated oxygen sensor displayed on the GTS.
Tech Tips
The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
The heated oxygen sensor has a maximum output delay of approximately 20 seconds.
Standard Voltage |
---|
Fluctuates between 0.4 V or less, and 0.55 V or higher. |
Result | |||
---|---|---|---|
|
NG |
CHECK FOR EXHAUST GAS LEAK Click here |
OK |
PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)
Connect the GTS to the DLC3.
Start the engine.
Turn the GTS on.
Warm up the engine.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / All Data / AFS Voltage B1S1 and O2S B1S2.
Active Test Display |
---|
Control the Injection Volume for A/F Sensor |
Data List Display |
---|
AFS Voltage B1S1 |
O2S B1S2 |
Change the fuel injection volume using the GTS, and monitor the voltage output of the air fuel ratio sensor and heated oxygen sensor displayed on the GTS.
Tech Tips
The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
The air fuel ratio sensor is displayed as AFS Voltage B1S1, and the heated oxygen sensor is displayed as O2S B1S2 on the GTS.
The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.
Result | |||||||||
---|---|---|---|---|---|---|---|---|---|
|
Tech Tips
A normal heated oxygen sensor voltage (O2S B1S2) reacts in accordance with increases and decreases in fuel injection volumes. When the air fuel ratio sensor voltage (AFS Voltage B1S1) remains at either less or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.
OK |
CHECK ENGINE TO DETERMINE CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO (FUEL INJECTOR ASSEMBLY, FUEL SYSTEM, INTAKE SYSTEM, ETC.) Click here |
NG |
REPLACE AIR FUEL RATIO SENSOR
Replace the air fuel ratio sensor.
Result | ||
---|---|---|
|
NEXT |
PERFORM CONFIRMATION DRIVING PATTERN
Perform the Confirmation Driving Pattern.
Result | ||
---|---|---|
|
NEXT |
CHECK WHETHER DTC OUTPUT RECURS (DTC P0136 OR P0138)
Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Tester Display |
---|
All Readiness |
Input the DTC: P0136 or P0138.
Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again but increase the vehicle speed.
Result | ||||||
---|---|---|---|---|---|---|
|
A |
END |
B |
REPLACE HEATED OXYGEN SENSOR Click here |
CHECK FOR EXHAUST GAS LEAK
Check for exhaust gas leaks.
OK |
---|
No gas leaks. |
Tech Tips
Perform "Inspection After Repair" after repairing or replacing the exhaust system.
Result | |||
---|---|---|---|
|
NG |
REPAIR OR REPLACE EXHAUST GAS LEAK POINT |
OK |
INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
Inspect the heated oxygen sensor.
Result | |||
---|---|---|---|
|
NG |
REPLACE HEATED OXYGEN SENSOR Click here |
OK |
CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)
Disconnect the heated oxygen sensor connector.
Disconnect the ECM connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance | ||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Result | |||
---|---|---|---|
|
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
OK |
REPLACE HEATED OXYGEN SENSOR
Replace the heated oxygen sensor.
Result | ||
---|---|---|
|
NEXT |
PERFORM CONFIRMATION DRIVING PATTERN
Perform Confirmation Driving Pattern.
Result | ||
---|---|---|
|
NEXT |
CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137 OR P0138)
Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Tester Display |
---|
All Readiness |
Input DTC: P0136, P0137 or P0138.
Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again but increase the vehicle speed.
Result | ||||||
---|---|---|---|---|---|---|
|
A |
END |
B |
REPLACE AIR FUEL RATIO SENSOR Click here |