P0137

2AR-FE ENGINE CONTROL: SFI SYSTEM: P0136-P0139: Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)

DTC P0136 - Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)

DTC P0137 - Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)

DTC P0138 - Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)

DTC P0139 - Oxygen Sensor Circuit Slow Response (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 Three-way Catalytic Converter (TWC) is used. For the most efficient use of the Three-way Catalytic Converter (TWC), the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio. 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 Three-way Catalytic Converter (TWC), and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with a 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 rich. The heated oxygen sensor informs the ECM that the post-Three-way Catalytic Converter (TWC) air-fuel ratio is lean (low voltage, i.e. below 0.45 V).

Conversely, when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, the oxygen concentration in the exhaust gas becomes lean. The heated oxygen sensor informs the ECM that the post-Three-way Catalytic Converter (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 Three-way Catalytic Converter (TWC) is rich or lean, and adjusts the fuel injection time accordingly. Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in primary air-fuel ratio control.









MONITOR DESCRIPTION

Active Air-fuel Ratio Control

The ECM usually performs air-fuel ratio feedback control so that the air fuel ratio sensor output indicates a near stoichiometric air-fuel ratio. 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 15 to 20 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.

Abnormal Voltage Output of Heated Oxygen Sensor (DTC P0136)

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 increase to a value higher than 0.69 V during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormal and stores DTC P0136.





Open in Heated Oxygen Sensor Circuit (DTC P0137)

During active air fuel ratio control, the ECM calculates the oxygen storage capacity* of the three-way catalytic converter by forcibly regulating the air fuel ratio to become rich or lean.

If the heated oxygen sensor has an open circuit, or the voltage output of the sensor noticeably decreases, the oxygen storage capacity indicates an extraordinarily 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 0.21 V or less (lean), the ECM interprets this as an abnormally low sensor output voltage and stores DTC P0137.

HINT
*: The three-way catalytic converter has the capability to store oxygen. The oxygen storage capacity and the emission purification capacity of the three-way catalytic converter are mutually related. The ECM determines whether the catalyst has deteriorated based on the calculated oxygen storage capacity value P0420.





High or Low Impedance of Heated Oxygen Sensor (DTC P0136 or P0137)





During normal air-fuel ratio feedback control, there are small variations in the exhaust gas oxygen concentration. In order to continuously monitor the slight variations in the heated oxygen sensor signal while the engine is running, the impedance* of the sensor is measured by the ECM. The ECM determines that there is a malfunction in the sensor when the measured impedance deviates from the standard range.

*: The effective resistance in an alternating current electrical circuit.

HINT
- The impedance cannot be measured using an ohmmeter.
- DTC P0136 indicates deterioration of the heated oxygen sensor. The ECM stores this DTC by calculating the impedance of the sensor when the typical enabling conditions are satisfied (2 driving cycles).
- DTC P0137 indicates an open or short circuit in the heated oxygen sensor (2 driving cycles). The ECM stores this DTC when the impedance of the sensor exceeds the threshold of 15 kOhms.

Extremely High Output Voltage of Heated Oxygen Sensor (DTC P0138)

The ECM continuously monitors the heated oxygen sensor output voltage while the engine is running.

DTC P0138 is stored if the heated oxygen sensor voltage output is higher than 1.2 V for 10 seconds or more.

Abnormal Voltage Output of Heated Oxygen Sensor During Fuel Cut (P0139)

The sensor output voltage drops below 0.2 V (extremely lean status) immediately when the vehicle decelerates and fuel cut is operating. If the voltage does not drop below 0.2 V within 7 seconds, or does not drop from 0.35 V to 0.2 V within 1 second, the ECM determines that the sensor response has deteriorated, illuminates the MIL and stores a DTC.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All





Heated Oxygen Sensor Output Voltage (Abnormal Voltage Output and Low Voltage)





Heated Oxygen Sensor Impedance (Low)





Heated Oxygen Sensor Impedance (High)





Heated Oxygen Sensor Output Voltage (Extremely High)





Heated Oxygen Sensor Output Voltage During Fuel Cut





TYPICAL MALFUNCTION THRESHOLDS

Heated Oxygen Sensor Output Voltage (Abnormal Voltage Output)





Heated Oxygen Sensor Output Voltage (Low)





Heated Oxygen Sensor Impedance (Low)





Heated Oxygen Sensor Impedance (High)





Heated Oxygen Sensor Output Voltage (Extremely High)





Heated Oxygen Sensor Output Voltage During Fuel Cut





COMPONENT OPERATING RANGE





MONITOR RESULT

Refer to detailed information in Checking Monitor Status Mode 6 Data.

P0138: O2 Sensor / MAX VOL B1S2





P0139: O2 Sensor / RL F/C B1S2





P0139: O2 Sensor / F/C TIME B1S2





P0136: O2 Sensor / MAX OSC B1S2





CONFIRMATION DRIVING PATTERN

P0136, P0137 and P0138





1. Connect the Techstream to the DLC3.

2. Turn the ignition switch to ON and turn the Techstream on.

3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).

4. Turn the ignition switch off and wait for at least 30 seconds.

5. Turn the ignition switch to ON and turn the Techstream on [A].

6. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [B].

7. With the transmission in 4th gear or higher, drive the vehicle at a speed between 60 and 120 km/h (40 and 75 mph) for 10 minutes or more [C].

CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.

8. Enter the following menus: Powertrain / Engine / Trouble Codes [D].

9. Read the pending DTCs.

HINT
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.

10. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

11. Input the DTC: P0136, P0137 or P0138.

12. Check the DTC judgment result.





HINT
- 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 UNKNOWN, perform steps [C] through [D].

13. If no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.

HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

P0139





1. Connect the Techstream to the DLC3.

2. Turn the ignition switch to ON and turn the Techstream on.

3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).

4. Turn the ignition switch off and wait for at least 30 seconds.

5. Turn the ignition switch to ON and turn the Techstream on [A].

6. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [B].

7. Drive the vehicle at 60 km/h (40 mph), and then decelerate the vehicle by releasing the accelerator pedal for 5 seconds or more to perform the fuel-cut [C].

CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.

8. Enter the following menus: Powertrain / Engine / Trouble Codes [D].

9. Read the DTCs.

HINT
- If a pending DTC or current DTC is output, the system is malfunctioning.
- If a pending DTC or current DTC is not output, perform the following procedure.

10. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

11. Input the DTC: P0139.

12. Check the DTC judgment result.





HINT
- 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 UNKNOWN, shift the transmission to 2nd gear, and then perform steps [C] and [D] again.

13. If no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.

HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

WIRING DIAGRAM





INSPECTION PROCEDURE

HINT
Malfunctioning areas can be identified by performing the Control the Injection Volume function provided in the Active Test. The Control the Injection Volume 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 operation using the Techstream.

(a) Connect the Techstream to the DLC3.
(b) Start the engine and turn the Techstream on.
(c) Warm up the engine and run the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(d) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume.
(e) Perform the Active Test operation with the engine idling.
(f) Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.

HINT
- Change the fuel injection volume within the range of -12.0% to +12.0%. The injection volume can be changed in fine gradations.
- 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.





NOTICE:
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.





HINT
- Following the Control the Injection Volume 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 / Active Test / Control the Injection Volume / All Data / AFS Voltage B1S1 and O2S B1S2.
- Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. 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.
- If the OX1B wire from the ECM connector is short-circuited to the +B wire, DTC P0136 will be stored.
- Sensor 1 refers to the sensor closest to the engine assembly.
- Sensor 2 refers to the sensor farthest away from the engine assembly.

PROCEDURE

1. READ OUTPUT DTC

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Trouble Codes.

(e) Read the DTCs.

Result





E -- GO TO DTC CHART Engine Control - SFI System

D -- CHECK FOR EXHAUST GAS LEAK

C -- PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)

B -- CHECK FOR EXHAUST GAS LEAK
A -- Continue to next step.

2. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)





(a) Disconnect the heated oxygen sensor connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





Text in Illustration





NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)

(a) Turn the ignition switch off and wait for 5 minutes.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Removal

4. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

(c) Turn the Techstream on.

(d) Warm up the engine.

(e) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume / All Data / O2S B1S2.

(f) Change the fuel injection volume using the Techstream, monitoring the voltage output of the heated oxygen sensors displayed on the Techstream.

HINT
- Change the fuel injection volume within the range of -12% to +12%. The injection volume can be changed in fine gradations within this range.
- 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.

Standard voltage:

Fluctuates between 0.4 V or less and 0.5 V or higher.

NG -- CHECK FOR EXHAUST GAS LEAK
OK -- Continue to next step.

5. PERFORM ACTIVE TEST USING TECHSTREAM (INJECTION VOLUME)

(a) Connect the Techstream to the DLC3.

(b) Turn the Techstream on.

(c) Start the engine.

(d) Warm up the engine.

(e) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume.

(f) Change the fuel injection volume using the Techstream and monitor the voltage output of the air fuel ratio and heated oxygen sensors displayed on the Techstream.

HINT
- Change the fuel injection volume within the range of -12% to +12%. The injection volume can be changed in fine gradations within this range.
- The air fuel ratio sensor is displayed as AFS Voltage B1S1, and the heated oxygen sensor is displayed as O2S B1S2 on the Techstream.
- 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.

Result





HINT
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 remains at either below or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.





NG -- REPLACE AIR FUEL RATIO SENSOR

OK -- CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO AND REPAIR CAUSE (FUEL INJECTOR ASSEMBLY, FUEL PRESSURE, GAS LEAK FROM SYSTEM)

6. CHECK FOR EXHAUST GAS LEAK

(a) Check for exhaust gas leakage.

OK:

No gas leakage.

NG -- REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK -- Continue to next step.

7. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE) P0037

NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.

8. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)

(a) Disconnect the heated oxygen sensor connector.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

9. REPLACE HEATED OXYGEN SENSOR

(a) Replace the heated oxygen sensor Removal.

NEXT -- Continue to next step.

10. PERFORM CONFIRMATION DRIVING PATTERN

(a) Perform Confirmation Driving Pattern (P0136, P0137 and P0138).

NEXT -- Continue to next step.

11. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137 OR P0138)

(a) Connect the Techstream to the DLC3.

(b) Turn the Techstream on.

(c) Enter the following menus: Powertrain / Engine / Utility / All Readiness.

(d) Input DTCs: P0136, P0137 and P0138.

(e) Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again but increase the vehicle speed.

Result





B -- END

A -- REPLACE AIR FUEL RATIO SENSOR Removal

12. REPLACE AIR FUEL RATIO SENSOR

(a) Replace the air fuel ratio sensor Removal.

NEXT -- Continue to next step.

13. PERFORM CONFIRMATION DRIVING PATTERN

(a) Perform Confirmation Driving Pattern (P0136, P0137 and P0138).

NEXT -- Continue to next step.

14. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137 OR P0138)

(a) Connect the Techstream to the DLC3.

(b) Turn the Techstream on.

(c) Enter the following menus: Powertrain / Engine / Utility / All Readiness.

(d) Input DTCs: P0136, P0137 or P0138.

(e) Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again but increase the vehicle speed.

Result





B -- END

A -- REPLACE HEATED OXYGEN SENSOR Removal

15. CHECK FOR EXHAUST GAS LEAK

(a) Check for exhaust gas leak.

OK:

No gas leakage.

NG -- REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK -- Continue to next step.

16. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)

(a) Turn the ignition switch off and wait for 5 minutes.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

17. PERFORM CONFIRMATION DRIVING PATTERN

(a) Perform Confirmation Driving Pattern (P0139).

NEXT -- Continue to next step.

18. READ DTC OUTPUT (CHECK WHETHER DTC P0139 IS OUTPUT AGAIN)

(a) Read the DTCs DTC Check / Clear.

Result





B -- CHECK FOR INTERMITTENT PROBLEMS Check for Intermittent Problems

A -- REPLACE HEATED OXYGEN SENSOR Removal