P0136

2UR-GSE ENGINE CONTROL: SFI SYSTEM: P0136-P0139,P0156-P0159: Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)

DESCRIPTION

HINT
Sensor 2 refers to the sensor mounted behind the three-way catalytic converter and located far from the engine assembly.

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon and nitrogen oxide (NOx) components in the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, 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 three-way catalytic converter, 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 rich. The heated oxygen sensor informs the ECM that the post-three-way catalytic converter 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 becomes lean. The heated oxygen sensor informs the ECM that the post-three-way catalytic converter air fuel ratio is rich (high voltage, i.e. more 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 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 the primary air fuel ratio control.









MONITOR DESCRIPTION

1. 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 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 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 set.

2. Abnormal Voltage Output of Heated Oxygen Sensor (DTC P0136 and P0156)

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 more than 0.59 V during active air fuel ratio control, the ECM determines that the sensor voltage output is abnormal and sets DTCs P0136 or P0156.





3. Open or Short in Heated Oxygen Sensor Circuit (DTCs P0137 and P0157)

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, 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 less than 0.21 V (lean), the ECM interprets this as an abnormally low sensor output voltage and sets DTC P0137 or P0157.

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.





4. High or Low Impedance of Heated Oxygen Sensor (DTCs P0136 and P0156 or P0137 and P0157)

During normal air fuel ratio feedback control, there are small variations in the exhaust gas oxygen concentration. In order to continuously monitor the slight variation of 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.
- DTCs P0136 and P0156 indicate the deterioration of the heated oxygen sensor. The ECM sets the DTCs by calculating the impedance of the sensor when the typical enabling conditions are satisfied (2 driving cycles).
- DTCs P0137 and P0157 indicate an open or short circuit in the heated oxygen sensor (2 driving cycles). The ECM sets the DTCs when the impedance of the sensor exceeds the threshold 15 kOhms.

5. Extremely High Output Voltage of Heated Oxygen Sensor (DTC P0138 or P0158)

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 more than 1.2 V for 10 seconds or more.

6. Abnormal Voltage Output of Heated Oxygen Sensor During Fuel cut (DTC P0139 or P0159)

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

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All





Heated Oxygen Sensor Output Voltage (Output Voltage, High Voltage and Low Voltage)





Heated Oxygen Sensor Impedance (Low Impedance)





Heated Oxygen Sensor Impedance (High Impedance)





Heated Oxygen Sensor Output Voltage (Extremely High)





Heated Oxygen Sensor Voltage During Fuel Cut





TYPICAL MALFUNCTION THRESHOLDS

Heated Oxygen Sensor Output Voltage (Output Voltage)





Heated Oxygen Sensor Output Voltage (Low Output Voltage)





Heated Oxygen Sensor Impedance (Low Impedance)





Heated Oxygen Sensor Impedance (High Impedance)





Heated Oxygen Sensor Output Voltage (Extremely High)





Heated Oxygen Sensor Voltage During Fuel cut





COMPONENT OPERATING RANGE





MONITOR RESULT

Refer to Checking Monitor Status Mode 6 Data.

CONFIRMATION DRIVING PATTERN

P0136, P0137, P0138, P0156, P0157 and P0158





1. Connect the Techstream to the DLC3.

2. Turn the engine switch on (IG) and turn the Techstream on.

3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Reading and Clearing Diagnostic Trouble Codes.

4. Turn the engine switch off and wait for 30 seconds.

5. Turn the engine switch on (IG) 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 37 to 75 mph (60 to 120 km/h) 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 / Pending.

9. Read the pending DTC [D].

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, P0138, P0156, P0157 or P0158.

12. Check the DTC judgment result.





HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows INCOMPLETE or UNKNOWN, perform step [C] again.

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

14. Check the DTC judgment result.

HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.

15. If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

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

P0139 and P0159





1. Connect the Techstream to the DLC3.

2. Turn the engine switch on (IG) and turn the Techstream on.

3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Reading and Clearing Diagnostic Trouble Codes.

4. Turn the engine switch off and wait for 30 seconds.

5. Turn the engine switch on (IG) 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 37 mph (60 km/h), 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 / Pending.

9. Read the pending DTC [D].

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 or P0159.

12. Check the DTC judgment result.





HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows INCOMPLETE or UNKNOWN, shift the transmission to 2nd gear, and then perform step [C] again.

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

14. Check the DTC judgment result.

HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.

15. If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

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 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 Techstream.

(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(e) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor.
(f) Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume.)
(g) Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 or AFS Voltage B2S1 and O2S B1S2 or O2S B2S2) displayed on the Techstream.

HINT
- The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.





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.





- 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 / Active Test / Control the Injection Volume for A/F Sensor / All Data / AFS Voltage B1S1 or AFS Voltage B2S1 and O2S B1S2 or O2S B2S2 then press the graph button on the Data List view.

HINT
- Bank 1 refers to the bank that includes the No. 1 cylinder*.
*: The No. 1 cylinder is the cylinder which is farthest from the transmission.
- Bank 2 refers to the bank that does not include the No. 1 cylinder.
- 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 Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
- If the OX1B or OX2B wire from the ECM connector is short-circuited to the +B wire, DTC P0136 or P0156 may be set.

PROCEDURE

1. READ DTC OUTPUT (DTC P0136, P0137, P0138, P0139, P0156, P0157, P0158 OR P0159)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

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

(e) Read the DTCs.

Result:





E -- GO TO DTC CHART SFI System

D -- INSPECT FOR EXHAUST GAS LEAK

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

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

2. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)

(a) Turn the engine switch off and wait for 5 minutes or more.

(b) Disconnect the heated oxygen sensor connector.





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

Standard Resistance:

Bank 1
Bank 2










(d) Reconnect the heated oxygen sensor connector.

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

3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)

(a) Disconnect the ECM connector.

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

Standard Resistance:

Bank 1
Bank 2










(c) Reconnect the ECM connector.

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 or O2S B2S2.

(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 0.55 V or higher.

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

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

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Start the engine and warm it up.

(e) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume / AFS Voltage B1S1, AFS Voltage B2S1, O2S B1S2 and O2S B2S2.

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

HINT
- Change the fuel injection volume within the range of -12% and +12%. The injection volume can be changed in fine graduations within the range.
- The air fuel ratio sensor is displayed as AFS Voltage B1S1 or AFS Voltage B2S1, and the heated oxygen sensor is displayed as O2S B1S2 or O2S B2S2 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 or O2S B2S2) reacts in accordance with increases and decreases in fuel injection volumes. When the air fuel ratio sensor voltage remains at either less or more 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 ENGINE TO DETERMINE CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO P0171

6. INSPECT FOR EXHAUST GAS LEAK

(a) Check for exhaust gas leaks from the exhaust manifold sub-assembly and exhaust pipes.

OK:

No gas leaks.

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

7. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

(a) Disconnect the heated oxygen sensor connector.





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

Standard Resistance (Bank 1 Sensor 2):





Standard Resistance (Bank 2 Sensor 2):





(c) Reconnect the heated oxygen sensor connector.

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 (Check for Open):

Bank 1
Bank 2










Standard Resistance (Check for Short):

Bank 1
Bank 2










(d) Reconnect the heated oxygen sensor connector.

(e) Reconnect the ECM connector.

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) Refer to the confirmation driving pattern for P0136, P0137, P0138, P0156, P0157 and P0158.

NEXT -- Continue to next step.

11. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137, P0138, P0156, P0157 OR P0158)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

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

(e) Input the DTC: P0136, P0137, P0138, P0156, P0157 or P0158.

(f) Check the DTC Monitor is NORMAL. If DTC Monitor is INCOMPLETE, perform the driving pattern adding the vehicle speed.

Result:





B -- REPLACE AIR FUEL RATIO SENSOR Removal

A -- END

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) Refer to the confirmation driving pattern for P0136, P0137, P0138, P0156, P0157 and P0158.

NEXT -- Continue to next step.

14. CHECK WHETHER DTC OUTPUT RECURS (P0136, P0138, P0156 OR P0158)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

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

(e) Input DTCs: P0136, P0138, P0156 and P0158.

(f) Check that DTC Monitor is NORMAL. If DTC Monitor is INCOMPLETE, perform the driving pattern adding the vehicle speed.

Result:





B -- REPLACE HEATED OXYGEN SENSOR Removal

A -- END

15. INSPECT FOR EXHAUST GAS LEAK

(a) Check for exhaust gas leaks from the exhaust manifold sub-assembly and exhaust pipes.

OK:

No gas leaks.

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

16. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)

(a) Turn the engine switch off and wait for 5 minutes or more.

(b) Disconnect the ECM connector.

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

Standard Resistance:

Bank 1
Bank 2










(d) Reconnect the ECM connector.

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

17. PERFORM CONFIRMATION DRIVING PATTERN

(a) Perform Confirmation Driving Pattern (P0139 and P0159).

NEXT -- Continue to next step.

18. READ DTC OUTPUT (DTC P0139 OR P0159)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

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

(e) Input DTCs: P0139 and P0159.

Result:





B -- REPLACE HEATED OXYGEN SENSOR Removal

A -- CHECK FOR INTERMITTENT PROBLEMS Check For Intermittent Problems