P0158

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 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)

CAUTION / NOTICE / HINT
HINT: Sensor 2 refers to the sensor mounted behind the Three-Way Catalytic Converter (TWC) and located far from the engine assembly.

DESCRIPTION

A three-way catalytic converter (TWC) is used in order to convert the carbon monoxide (CO), hydro carbon (HC), and nitrogen oxides (HOx) 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 helping the ECM to deliver accurate air-fuel ratio control, a Heated Oxygen (HO2) sensor becomes 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

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).

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 or 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.






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, 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 30 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.






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.





HINT:
- 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 15 kOhms.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All:





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





Heated Oxygen Sensor Impedance (Low):





Heated Oxygen Sensor Impedance (High):





Heated Oxygen Sensor Output Voltage (Extremely High):





TYPICAL MALFUNCTION THRESHOLDS

Heated Oxygen Sensor Output Voltage (Output voltage):





Heated Oxygen Sensor Output Voltage (Low output voltage):





Heated Oxygen Sensor Output Voltage (High output voltage):





Heated Oxygen Sensor Impedance (Low):





Heated Oxygen Sensor Impedance (High):





Heated Oxygen Sensor Impedance (Extremely High):





COMPONENT OPERATING RANGE





MONITOR RESULT

Refer to CHECKING MONITOR STATUS Mode 6 Data.

WIRING DIAGRAM





CONFIRMATION DRIVING PATTERN
HINT:
- This confirmation driving pattern is used in steps 5, 8 and 11 of the following diagnostic troubleshooting procedure when using the intelligent tester.
- Performing this confirmation pattern will activate the Heated Oxygen (HO2) sensor monitor. (The catalyst monitor is performed simultaneously.) This is very useful for verifying the completion of a repair.





1 Connect the intelligent tester to the DLC3 (Procedure A).





2 Turn the ignition switch to the ON position (Procedure B).
3 Turn the tester on (Procedure C).
4 Clear the DTCs (where set) DTC Check / Clear (Procedure D).
5 Select the following menu items: DIAGNOSIS / CARB OBD II / READINESS TESTS (Procedure E).
6 Check that O2S EVAL is INCMPL (incomplete) (Procedure F).
7 Start the engine and warm it up (Procedure G).
8 Drive the vehicle at between 38 mph and 75 mph (60 km/h and 120 km/h) for at least 10 minutes (Procedure H).
9 Note the state of the Readiness Tests items. Those items will change to COMPL (complete) as O2S EVAL monitor operates (Procedure I).
10 On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES and check if any DTCs (any pending DTCs) are set (Procedure J).
HINT: If O2S EVAL does not change to COMPL, and any pending DTCs fail to set, extend the driving time.

INSPECTION PROCEDURE
HINT: For use of the intelligent tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL function can help to 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 A/F CONTROL operation using the intelligent tester.

1 Connect the intelligent tester to the DLC3.
2 Start the engine and turn the tester on.
3 Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
4 Select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
5 Perform the A/F CONTROL 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 B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.
HINT:
- The A/F CONTROL 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.

Standard voltage:





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 A/F CONTROL procedure enables technicians to check the graph of the voltage outputs of both the A/F and HO2 sensors.
- To display the graph, select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2. Press the YES button and then the ENTER button. Then press the F4 button.
HINT:
- If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
- Read freeze frame data using the intelligent tester. 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 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 intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and turn the tester on.
(c) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(d) Read the DTCs.
Result:






C -- READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
B -- CHECK FOR EXHAUST GAS LEAKAGE
A -- Continue to next step.
2. READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and turn the tester on.
(c) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / O2S B1S2 or O2S B2S2.
(d) Allow the engine to idle.
(e) Read the Heated Oxygen (HO2) sensor output voltage while idling.
Result:






B -- CHECK AIR FUEL RATIO SENSOR
A -- 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 E8 or E9 ECM connector.
(c) Measure the resistance.
Standard resistance:





(d) Reconnect the ECM connector.
NG -- INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)
OK -- REPLACE ECM
4. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)





(a) Disconnect the H20 heated oxygen sensor connector (Bank 1 Sensor 2) or H11 heated oxygen sensor connector (Bank 2 Sensor 2).
(b) Measure the resistance between the terminals of the HO2 sensor connector.
Standard resistance:
Bank 1






Bank 2:






(c) Reconnect the HO2 sensor connector.
NG -- REPLACE HEATED OXYGEN SENSOR
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR
5. CHECK AIR FUEL RATIO SENSOR
HINT: This A/F sensor test is to check the A/F sensor current during the fuel-cut. When the sensor is normal, the sensor current will indicate below 3 mA in this test.
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and turn the tester on.
(c) Start the engine and warm it up with all the accessories switched off.
(d) Drive the vehicle at 40 mph (60 km/h) or more for 10 minutes or more.
(e) Stop the vehicle.
(f) Accelerate the vehicle until 40 mph (60 km/h) or more and decelerate for 3 seconds or more. Perform this 3 times.





(g) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / MONITOR INFO and MONITOR RESULT.
(h) Confirm that RANGE B1 S1 is either PASS or FAIL.
(i) Select RANGE B1 S1 and press ENTER.
(j) Read the test value.
Standard:
Less than 3.0 mA
NOTE: Do not turn the ignition switch off, during this step because the test results will be lost.

OK -- REPLACE HEATED OXYGEN SENSOR
NG -- REPLACE AIR FUEL RATIO SENSOR
6. READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and turn the tester on.
(c) Start the engine.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / O2S B1S2 or O2S B1S2.
(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:
Fluctuates between 0.4 V or less and 0.5 V or more.
NG -- CHECK FOR EXHAUST GAS LEAKAGE
OK -- Continue to next step.
7. PERFORM CONFIRMATION DRIVING PATTERN
(a) Perform confirmation driving pattern Monitors, Trips, Drive Cycles and Readiness Codes.
NEXT -- Continue to next step.
8. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136 OR P0156)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and turn the tester on.
(c) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(d) Read the DTCs.
Result:






B -- CHECK FOR INTERMITTENT PROBLEMS
A -- 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 Monitors, Trips, Drive Cycles and Readiness Codes.
NEXT -- Continue to next step.
11. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136 OR P0156)
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and turn the tester on.
(c) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(d) Read the DTCs.
Result:






B -- REPAIR END
A -- Continue to next step.
12. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (INJECTION VOLUME)
(a) Connect the intelligent tester to the DLC3.
(b) Start the engine and turn the tester on.
(c) Warm up the engine.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / INJ VOL.
(e) Change the fuel injection volume using the tester, while monitoring the voltage output of Air-Fuel Ratio (A/F) and HO2 sensors displayed on the tester.
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 B1S1 or AFS B2S1, and the HO2 sensor is displayed as O2S B1S2 or O2S B2S2, on the intelligent tester.

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 at either less or more than 3.3 V despite the HO2 sensor indicating a normal reaction, the A/F sensor is malfunctioning.





NG -- REPLACE AIR FUEL RATIO SENSOR
OK -- CHECK AND REPLACE EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO (INJECTOR, FUEL PRESSURE, GAS LEAKAGE FROM EXHAUST SYSTEM)
13. CHECK FOR EXHAUST GAS LEAKAGE
OK:
No gas leakage.
NG -- REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK -- Continue to next step.
14. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)





(a) Disconnect the H20 heated oxygen sensor connector (Bank 1 Sensor 2) or H11 heated oxygen sensor connector (Bank 2 Sensor 2).
(b) Measure the resistance between the terminals of the HO2 sensor connector.
Standard resistance:
Bank 1






Bank 2






(c) Reconnect the HO2 sensor connector.
NG -- REPLACE HEATED OXYGEN SENSOR
OK -- Continue to next step.
15. INSPECT EFI MAIN RELAY





(a) Remove the EFI MAIN relay from the engine room R/B.
(b) Measure the EFI MAIN relay resistance.
Standard resistance:






NG -- REPLACE EFI MAIN RELAY
OK -- Continue to next step.
16. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)





(a) Disconnect the H11 or H20 HO2 sensor connector.
(b) Turn the ignition switch to the ON position.
(c) Measure the voltage between the +B terminal of the HO2 sensor connector and body ground.
Standard voltage:





(d) Turn the ignition switch off.
(e) Disconnect the E8 and E9 ECM connectors.
(f) Measure the resistance.
Standard resistance:
Check for open






Check for short






(g) Reconnect the HO2 sensor connector.
(h) Reconnect the ECM connectors.





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE HEATED OXYGEN SENSOR