P0136

2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0136: 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)

DTC P0156 - Oxygen Sensor Circuit Malfunction (Bank 2 Sensor 2)

DTC P0157 - Oxygen Sensor Circuit Low Voltage (Bank 2 Sensor 2)

DTC P0158 - Oxygen Sensor Circuit High Voltage (Bank 2 Sensor 2)

DTC P0159 - Oxygen Sensor Circuit Slow Response (Bank 2 Sensor 2)

CAUTION / NOTICE / HINT

DESCRIPTION

A three-way catalytic converter (TWC) is used in order to convert the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) into less harmful substances. To allow the TWC to function effectively, it is necessary to keep the air-fuel ratio of the engine near the stoichiometric air-fuel ratio. For the purpose of helping the ECM to deliver accurate air-fuel ratio control, the Heated Oxygen (HO2) sensor is used.
The HO2 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 becomes rich. The HO2 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 becomes lean. The HO2 sensor informs the ECM that the post-TWC air-fuel ratio is rich (high voltage, i.e. more than 0.45 V). The HO2 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 HO2 sensor to determine whether the air-fuel ratio after the TWC is rich or lean, and adjusts the fuel injection time accordingly. Thus, if the HO2 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 (A/F) 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 (HO2) 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, one of the following DTCs is set: DTC P0136 or P0156 (abnormal voltage output), P0137 or P0157 (open circuit) or P0138 or P0158 (short circuit).
2. Abnormal Voltage Output of HO2 Sensor (DTCs 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 HO2 sensor voltage does not decrease to less than 0.21 V and does not increase 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 and P0156.

3. Open or Short in Heated Oxygen (HO2) Sensor Circuit (DTCs P0137 and P0157 or P0138 and P0158)
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 HO2 sensor has an open or short circuit, or the voltage output of the sensor noticeably decreases, the OSC indicates an extraordinarily high value. Even if the ECM attempts to continue regulating the air-fuel ratio to become rich or lean, the HO2 sensor output does not change.
While performing active air-fuel ratio control, when the target air-fuel ratio is rich and the HO2 sensor voltage output is 0.21 V or less (lean), the ECM interprets this as an abnormally low sensor output voltage and sets DTC P0137 or P0157. When the target air-fuel ratio is lean and the voltage output is 0.59 V or more (rich) during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormally high, and sets DTC P0138 or P0158.
HINT: DTC P0138 or P0158 is also set if the HO2 sensor voltage output is more than 1.2 V for 10 seconds or more.
*: 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 P0420.

4. High or Low Impedance of Heated Oxygen (HO2) 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 HO2 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.
- The impedance cannot be measured using an ohmmeter.
- DTCs P0136 and P0156 indicate the deterioration of the HO2 sensor. The ECM sets the DTCs by calculating the impedance of the sensor when the typical enabling conditions are satisfied (1 driving cycle).
- DTCs P0137 and P0157 indicate an open or short circuit in the HO2 sensor (1 driving cycle). The ECM sets the DTCs when the impedance of the sensor exceeds the threshold of 15 kOhms.

5. Abnormal Voltage Output of Heated Oxygen Sensor During Fuel-cut (DTC P0139 and 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, the ECM determines that the sensor's response feature has deteriorated, illuminates the MIL and sets a DTC.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

All:

HO2S voltage (P0136, P0156), HO2S low voltage (P0137, P0157), HO2S high voltage (P0138, P0158):

HO2S low impedance (P0136, P0156):

HO2S high impedance (P0137, P0157):

HO2S high voltage (Extremely high) (P0138, P0158):

HO2 sensor voltage (during fuel cut) (P0139, P0159):

TYPICAL MALFUNCTION THRESHOLDS

HO2S voltage (P0136, P0156):

HO2S low impedance (P0136, P0156):

HO2S high impedance (P0137, P0157):

HO2S low voltage (P0137, P0157):

HO2S high voltage (P0138, P0158):

HO2S high voltage (Extremely high) (P0138, P0158):

HO2 sensor Voltage (During Fuel-cut) (P0139, P0159):

COMPONENT OPERATING RANGE

MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

1 Connect the Techstream to the DLC3.
2 Warm-up the engine until the engine coolant temperature is 75°C (167°F) or more [A].
3 Drive the vehicle at 40 to 75 mph (64 to 120 km/h) for at 10 minutes [B].
4 Drive the vehicle 40 mph (64 km/h) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times [C].
5 Turn the Techstream on.
6 Select the following menu items: Powertrain / Engine / Utility / All Readiness.
7 Input DTCs: P0136, P0137, P0138, P0156, P0157 and P0158.
8 Check that STATUS is NORMAL. If STATUS is INCOMPLETE, perform the drive pattern adding the vehicle speed and using the second gear to decelerate the vehicle.

INSPECTION PROCEDURE
HINT: Techstream only:
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 determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) 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.

1 Connect the Techstream to the DLC3.
2 Start the engine and turn the Techstream on.
3 Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
4 On the Techstream, enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor.
5 Perform the Control the Injection Volume for A/F Sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
6 Monitor the voltage outputs of the A/F and HO2 sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and 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 in the fuel injection volume.

NOTE:
The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) 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 A/F and HO2 sensors.
- To display the graph, enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor / AFS Voltage B1 S1 or AFS Voltage B2 S1 and O2S B1 S2 or O2S B2 S2 then press the graph button on the Data List view.
HINT:
- 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 Freeze Frame Data.
- If the OX1B wire from the ECM connector is short-circuited to the +B wire, DTC P0136 will be set.
- If the OX2B wire from the ECM connector is short-circuited to the +B wire, DTC P0156 will be set.

PROCEDURE

1. READ DTC OUTPUT
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine / Trouble Code.
(d) Read the DTCs.
Result:

D -- READ VALUE USING OXYGEN SENSOR (OUTPUT VOLTAGE)
C -- READ VALUE USING OXYGEN SENSOR (OUTPUT VOLTAGE)
B -- CHECK FOR EXHAUST GAS LEAKS
A -- Continue to next step.
2. READ VALUE USING OXYGEN SENSOR (OUTPUT VOLTAGE)
(a) Connect the Techstream to the DLC3.
(b) Enter the following menus: Powertrain / Engine / Data List / O2S B1 S2 or O2S B2 S2.
(c) Allow the engine to idle.
(d) Read the Heated Oxygen (HO2) sensor output voltage while idling.
Result:

OK -- CHECK AIR FUEL RATIO SENSOR CURRENT
NG -- Continue to next step.
3. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)

(a) Disconnect the B24 oxygen sensor connector (Bank 1 Sensor 2) or B25 oxygen sensor connector (Bank 2 sensor 2).
(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 oxygen sensor connector.
NG -- REPLACE HEATED OXYGEN SENSOR
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)

(a) Disconnect the B12 ECM connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

(c) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
5. CHECK AIR FUEL RATIO SENSOR CURRENT
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) and turn the Techstream on.
(c) Enter the following menu items: Powertrain / Engine / Monitor / O2 Sensor / Details.
(d) Check that RANGE B1S1 and RANGE B2S1 are either Pass or Fail.
If the Techstream shows Incomplete, re-check RANGE B1S1 and RANGE B2S1 after performing the drive pattern as listed below.
(e) Select RANGE B1S1 or RANGE B2S1 and press ENTER.
(f) Read the value.
Standard current:
Less than 3.0 mA
(g) Perform the drive pattern as listed below.

(1) Warm-up the engine until the engine coolant temperature is 75°C (167°F) or more.
(2) Drive the vehicle at 40 mph (64 km/h) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times.
If the Techstream shows Incomplete again, add the vehicle speed and use the second gear to decelerate the vehicle.
NG -- REPLACE AIR FUEL RATIO SENSOR
OK -- REPLACE HEATED OXYGEN SENSOR
6. READ VALUE USING OXYGEN SENSOR (OUTPUT VOLTAGE)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) and turn the Techstream on.
(c) Start the engine.
(d) Enter the following menus: Powertrain / Engine / Data List / O2S B1 S2 or O2S B2 S2.
(e) After warming up the engine, run the engine at an engine speed of 2,500 rpm for 3 minutes.
(f) Read the output voltage of the HO2 sensor when the engine rpm is suddenly increased.
HINT: Quickly accelerate the engine to 4,000 rpm 3 times using the accelerator pedal.

Standard voltage:
Fluctuates between 0.4 V or less and 0.55 V or more.
NG -- CHECK FOR EXHAUST GAS LEAKS
OK -- Continue to next step.
7. PERFORM ACTIVE TEST USING TECHSTREAM (INJECTION VOLUME)
(a) Connect the Techstream to the DLC3.
(b) Start the engine and turn the Techstream on.
(c) Warm up the engine.
(d) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume.
(e) Change the fuel injection volume using the Techstream, while monitoring the output voltage of Air-Fuel Ratio (A/F) and HO2 sensor displayed on the Techstream.
HINT:
- Change the fuel injection volume within the range of -12 % and +12 %. The injection volume can be changed in 1 % graduations within the range.
- The A/F sensor is displayed as AFS Voltage B1S1 or AFS Voltage B2S1, and the HO2 sensor is displayed as O2S B1S2 or O2S B2S2, on the Techstream.

Result:

HINT: A normal HO2 sensor voltage (O2S B1S2 or O2S B2S2) reacts in accordance with increases and decreases in fuel injection volumes. When the A/F sensor voltage remains either less or more than 3.25 V despite the HO2 sensor indicating a normal reaction, the A/F sensor is malfunctioning.

NG -- REPLACE AIR FUEL RATIO SENSOR
OK -- CHECK AND EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO (INJECTOR, FUEL PRESSURE, GAS LEAKAGE FROM EXHAUST SYSTEM)
8. CHECK FOR EXHAUST GAS LEAKS
(a) Check for exhaust gas leakage from the exhaust manifold and pipe.
OK:
No gas leakage.
NG -- REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK -- Continue to next step.
9. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

Standard resistance (Bank 2 sensor 2):

(c) Reconnect the oxygen sensor connector.
NG -- REPLACE HEATED OXYGEN SENSOR
OK -- Continue to next step.
10. INSPECT ENGINE ROOM JUNCTION BLOCK (EFI RELAY)

(a) Remove the engine room junction block from the engine room R/B.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

(c) Reinstall the engine room junction block.
NG -- REPLACE ENGINE ROOM JUNCTION BLOCK
OK -- Continue to next step.
11. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)

(a) Disconnect the B24 oxygen sensor connector (Bank 1 Sensor 2) or B25 oxygen sensor connector (Bank 2 sensor 2).
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:

(d) Turn the engine switch off.
(e) Disconnect the B12 ECM connector.
(f) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):

Standard resistance (Check for short):

(g) Reconnect the oxygen sensor connector.
(h) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
12. REPLACE HEATED OXYGEN SENSOR
(a) Replace the heated oxygen sensor.
NEXT -- Continue to next step.
13. PERFORM CONFIRMATION DRIVING PATTERN
(a) Connect the Techstream to the DLC3.
(b) Warm-up the engine until the engine coolant temperature is 75°C (167°F) or more.
(c) Drive the vehicle at 40 to 75 mph (64 to 120 km/h) for at 10 minutes.
(d) Drive the vehicle 40 mph (64 km/h) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times.
(e) Turn the Techstream on.
(f) Select the following menu items: Powertrain / Engine / Utility / All Readiness.
(g) Input DTCs: P0136, P0137, P0138, P0156, P0157 and P0158.
(h) Check that STATUS is NORMAL. If STATUS is INCOMPLETE, perform the driving pattern increasing the vehicle speed and using the second gear to decelerate the vehicle.

NG -- REPLACE AIR FUEL RATIO SENSOR
OK -- REPAIR COMPLETE
14. REPLACE AIR FUEL RATIO SENSOR
(a) Replace the air fuel ratio sensor.
NEXT -- Continue to next step.
15. PERFORM CONFIRMATION DRIVING PATTERN
(a) Connect the Techstream to the DLC3.
(b) Warm-up the engine until the engine coolant temperature is 75°C (167°F) or more.
(c) Drive the vehicle at 40 to 75 mph (64 to 120 km/h) for at 10 minutes.
(d) Drive the vehicle 40 mph (64 km/h) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times.
(e) Turn the Techstream on.
(f) Select the following menu items: Powertrain / Engine / Utility / All Readiness.
(g) Input DTCs: P0136, P0138, P0156 and P0158.
(h) Check that STATUS is NORMAL.

NG -- REPLACE HEATED OXYGEN SENSOR
OK -- REPAIR COMPLETE
16. READ VALUE USING OXYGEN SENSOR (OUTPUT VOLTAGE)
(a) Connect the Techstream to the DLC3.
(b) Enter the following menus: Powertrain / Engine / Data List / O2S B1 S2 or O2S B2 S2.
(c) Allow the engine to idle.
(d) Read the Heated Oxygen (HO2) sensor output voltage while idling.
Result:

OK -- READ VALUE USING DTC OUTPUT (DTC P0139 OR P0159 IS OUTPUT AGAIN)
NG -- Continue to next step.
17. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)

Standard resistance (Bank 2 sensor 2):

(c) Reconnect the oxygen sensor connector.
NG -- REPLACE HEATED OXYGEN SENSOR
OK -- Continue to next step.
18. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)

(a) Disconnect the B12 ECM connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

(c) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
19. READ VALUE USING DTC OUTPUT (DTC P0139 OR P0159 IS OUTPUT AGAIN)
(a) Connect the Techstream to the DLC3.
(b) Warm-up the engine until the engine coolant temperature is 75°C (167°F) or more.
(c) Drive the vehicle at 40 to 75 mph (64 to 120 km/h) for at 10 minutes.
(d) Drive the vehicle 40 mph (64 km/h) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times.
(e) Turn the Techstream on.
(f) Select the following menu items: Powertrain / Engine / Utility / All Readiness.
(g) Input DTCs: P0139 and P0159.
(h) Check that STATUS is NORMAL. If STATUS is INCOMPLETE, perform the driving pattern increasing the vehicle speed and using the second gear to decelerate the vehicle.

Result:

B -- REPLACE HEATED OXYGEN SENSOR
A -- CHECK INTERMITTENT PROBLEMS