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)

for Preparation Click here

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


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 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. To help 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 rich. 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 becomes lean. The heated oxygen sensor informs the ECM that the post-TWC 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 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 the primary air-fuel ratio control.

A088111E02


DTC No.
DTC Detection Conditions
Trouble Areas
P0136
  1. Abnormal output voltage
During active air-fuel ratio control, conditions (a) and (b) are met for certain period of time (1 trip detection logic):
(a) Heated oxygen sensor voltage does not decrease to less than 0.2 V
(b) Heated oxygen sensor voltage does not increase to more than 0.6 V
  1. Low impedance
Sensor impedance is less than 5 Ω for more than 30 seconds when ECM assumes sensor is being warmed up and operating normally (1 trip detection logic)
  1. Open or short in heated oxygen sensor (sensor 2) circuit
  2. Heated oxygen sensor (sensor 2)
  3. Heated oxygen sensor heater (sensor 2)
  4. Air-fuel Ratio (A/F) sensor (sensor 1)
  5. EFI relay
  6. Gas leakage from exhaust system
P0137
  1. Low voltage (open)
During active air-fuel ratio control, conditions (a) and (b) are met for certain period of time (1 trip detection logic):
(a) Heated oxygen sensor output voltage is less than 0.21 V
(b) Target air-fuel ratio rich
  1. High impedance
Sensor impedance is 15 Ω or more for more than 90 seconds when ECM assumes sensor is being warmed up and operating normally (1 trip detection logic)
  1. Open in heated oxygen sensor (sensor 2) circuit
  2. Heated oxygen sensor (sensor 2)
  3. Heated oxygen sensor heater (sensor 2)
  4. EFI relay
  5. Gas leakage from exhaust system
P0138
  1. High voltage (short)
During active air-fuel ratio control, conditions (a) and (b) are met for certain period of time (1 trip detection logic):
(a) heated oxygen sensor output voltage is 0.59 V or more
(b) Target air-fuel ratio lean
  1. Extremely high voltage (short)
Heated oxygen sensor output voltage exceeds 1.2 V for more than 10 seconds (1 trip detection logic)
  1. Short in heated oxygen sensor (sensor 2) circuit
  2. Heated oxygen sensor (sensor 2)
  3. ECM internal circuit malfunction

WIRING DIAGRAM


G038503E03


CONFIRMATION DRIVING PATTERN

HINT:
  1. This confirmation driving pattern is used in the following diagnostic troubleshooting inspection procedure when using the intelligent tester.
  2. Performing this confirmation 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.


A112072E01

(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch ON and turn the intelligent tester ON.
(c) Change the ECM from normal mode to check mode using the intelligent tester.
(d) Start the engine.
(e) Allow the engine to idle for 2 minutes.
(f) Warm up the engine until the engine coolant temperature reaches more than 75°C (167°F)
(g) Drive the vehicle between 64 and 113 km/h (40 and 70 mph) for at least 10 minutes.
(h) Stop the vehicle and allow the engine to idle for 20 seconds or more.

HINT:
If a malfunction exists, the MIL will illuminate during step (g).

NOTICE:
If the conditions in this test are not strictly followed, detection of a malfunction will not occur.


INSPECTION PROCEDURE

HINT:
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 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. On the tester, select the following menu items: Powertrain / Engine and ECT / 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 output voltage of the A/F and Heated oxygen sensors (AFS B1 S1 and O2S B1 S2) displayed on the tester.

HINT:
  1. The A/F Control operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
  2. Each sensor reacts in accordance with increases and decreases in the fuel injection volume.


Standard:

Tester Display
(Sensor)
Injection Volume
Status
Voltage
AFS B1 S1
(A/F)
+ 25%
Rich
Less than 3.0 V
AFS B1 S1
(A/F)
- 12.5%
Lean
More than 3.35 V
O2S B1 S2
(HO2)
+ 25%
Rich
More than 0.55 V
O2S B1 S2
(HO2)
- 12.5%
Lean
Less than 0.4 V

NOTICE:
The A/F sensor output has a few seconds of delay and the heated oxygen sensor output has about 20 seconds of delay at maximum.


Case
A/F Sensor (Sensor 1)
Output Voltage
HO2 Sensor (Sensor 2)
Output Voltage
Main Suspected Trouble Areas
1
Injection Volume
+25%
-12.5%
A103184
Injection Volume
+25%
-12.5%
A103184
-
Output Voltage
More than 3.35 V
Less than 3.0 V
A107708
Output Voltage
More than 0.55 V
Less than 0.4 V
A103186
2
Injection Volume
+25%
-12.5%
A103184
Injection Volume
+25%
-12.5%
A103184
  1. A/F sensor
  2. A/F sensor heater
  3. A/F sensor circuit
Output Voltage
Almost
no reaction
A103185
Output Voltage
More than 0.55 V
Less than 0.4 V
A103186
3
Injection Volume
+25%
-12.5%
A103184
Injection Volume
+25%
-12.5%
A103184
  1. HO2 sensor
  2. HO2 sensor heater
  3. HO2 sensor circuit
Output Voltage
More than 3.35 V
Less than 3.0 V
A107708
Output Voltage
Almost
no reaction
A103185
4
Injection volume
+25%
-12.5%
A103184
Injection Volume
+25%
-12.5%
A103184
  1. Injector
  2. Fuel pressure
  3. Gas leakage from exhaust system
    (Air-fuel ratio extremely lean or rich)
Output Voltage
Almost
no reaction
A103185
Output Voltage
Almost
no reaction
A103185
The following A/F Control procedure enables the technician to check and graph the output voltage of both A/F sensor and heated oxygen sensor.
To display the graph, select the following menu items on the tester: View / Line graph.

HINT:
  1. Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions 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.
  2. A low A/F sensor voltage could be caused by a rich air-fuel mixture. Check the conditions that would cause the engine to run with the rich air-fuel mixture.
  3. A high A/F sensor voltage could be caused by a lean air-fuel mixture. Check the conditions that would cause the engine to run with the lean air-fuel mixture.

1.CHECK OTHER DTC OUTPUT

  1. Read the DTC using the intelligent tester.

    Result:
    Display (DTC Output)
    		Proceed to
    P0138 is output
    		A
    P0137 is output
    		B
    P0136 is output
    		C

    HINT:
    If any codes besides P0136, P0137 and / or P0138 are output, perform the troubleshooting for those codes first.



B
Go to step 10

C
Go to step 7
A


2.READ VALUE OF DATA LIST

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch ON and turn the intelligent tester ON.

  1. Enter the following menus: Powertrain / Engine and ECT / Data List / O2S B1 S2.

  1. Run the engine at idle.

  1. Read the output voltage of the heated oxygen sensor during idling.

    Result:
    Heated Oxygen Sensor Output Voltage
    		Proceed to
    More than 1.2 V
    		A
    Less than 1.0 V
    		B



B
Go to step 5
A


3.CHECK WIRE HARNESS (CHECK FOR SHORT)
A065159E11

  1. Turn the ignition switch OFF and wait for 5 minutes.

  1. Disconnect the E12 ECM connector.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Specified Condition
    E12-2 (HT1B) - E12-25 (OX1B)
    		10 kΩ or higher
    E12-2 (HT1B) - E12-28 (E2)
    		10 kΩ or higher



OK
REPLACE ECM
NG


4.INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)
A062378E13

  1. Disconnect the H7 sensor connector.

  1. Measure the resistance of the sensor.

    Standard resistance:
    Tester Connection
    		Specified Condition
    2 (+B) - 4 (E)
    		10 kΩ or higher
    2 (+B) - 3 (OX)
    		10 kΩ or higher



OK
REPAIR OR REPLACE HARNESS AND CONNECTOR
NG

REPLACE HEATED OXYGEN SENSOR 

5.PERFORM CONFIRMATION DRIVING PATTERN

NEXT


6.READ OUTPUT DTC (CHECK MODE)

  1. Change the ECM to check mode with the intelligent tester. Enter the following menus: Powertrain / Engine and ECT / Check Mode.

  1. Warm up the engine and drive the vehicle at over 40 km/h (25 mph) for an accumulated total of 10 minutes.

    HINT:
    The 10 minutes of driving should be driven in one instance, but it is not necessary to maintain a speed of 40 km/h (25 mph) for 10 minutes consecutively.

  1. Read the DTC.

    Result:
    Display (DTC output)
    		Proceed to
    P0136 is output
    		A
    No DTC
    		B



B
CHECK FOR INTERMITTENT PROBLEMS
A

REPLACE HEATED OXYGEN SENSOR 

7.READ VALUE OF DATA LIST

  1. After warming up the engine, run the engine at 2,500 rpm for 3 minutes.

  1. Read the output voltage of the heated oxygen sensor when the engine rpm is suddenly increased.

    HINT:
    Quickly accelerate the engine to 4,000 rpm 3 times by depressing the accelerator pedal.

    Heated oxygen sensor output voltage:
    Alternates between 0.4 V or less and 0.5 V or more.



OK
Go to step 12
NG


8.CHECK FOR EXHAUST GAS LEAKAGE

OK:
No gas leakage.



NG
REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK


9.INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
A062378E13

  1. Disconnect the H7 sensor connector.

  1. Measure the resistance of the sensor.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    2 (+B) -1 (HT)
    		20°C (68°F)
    		11 to 16 Ω
    1 (HT) - 4 (E)
    		Always
    		10 kΩ or higher



NG
REPLACE HEATED OXYGEN SENSOR
OK


10.CHECK INTEGRATION RELAY (MAIN RELAY)
G039047E13

  1. Remove the integration relay from the engine room junction block.

  1. Measure the voltage of the MAIN relay.

    Standard voltage:
    Tester Connection
    		Condition
    		Specified Condition
    1J-5 - Body ground
    		Ignition switch ON
    		10 to 14 V



NG
REPLACE INTEGRATION RELAY
OK


11.CHECK WIRE HARNESS (HEATED OXYGEN SENSOR - ECM)
G038631E03

  1. Disconnect the H7 heated oxygen sensor connector.

  1. Disconnect the E12 ECM connector.



  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Specified Condition
    H7-1 (HT) - E11-2 (HT1B)
    H7-3 (OX) - E11-25 (OX1B)
    		Below 1 Ω
    H7-1 (HT) - E11-2 (HT1B) - Body ground
    H7-3 (OX) - E11-25 (OX1B) - Body ground
    		10 kΩ or higher


    B062793E08



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

REPLACE HEATED OXYGEN SENSOR 

12.PERFORM CONFIRMATION DRIVING PATTERN

HINT:
Clear all DTCs prior to performing the confirmation driving pattern.


NEXT


13.READ OUTPUT DTC (DTC P0136 IS OUTPUT AGAIN)

  1. Read DTC using the intelligent tester.

    Result:
    Display (DTC Output)
    		Proceed to
    P0136 is not output again
    		A
    P0136 is output again
    		B



A
CHECK FOR INTERMITTENT PROBLEMS
B


14.REPLACE HEATED OXYGEN SENSOR

NEXT


15.PERFORM CONFIRMATION DRIVING PATTERN

HINT:
Clear all DTCs prior to performing the confirmation driving pattern.


NEXT


16.READ OUTPUT DTC (DTC P0136 IS OUTPUT AGAIN)

  1. Read DTC using the intelligent tester.

    Result:
    Display (DTC Output)
    		Proceed to
    P0136 is not output again
    		A
    P0136 is output again
    		B



A
REPAIR COMPLETED
B


17.PERFORM ACTIVE TEST (INJECTOR VOLUME)

  1. Start the engine and warm it up.

  1. Connect the intelligent tester to the DLC3.

  1. Turn ON the ignition switch and the intelligent tester main switch.

  1. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.



  1. Using the intelligent tester, change the injection volume to check the A/F sensor output and heated oxygen sensor output values below.

    HINT:
    1. Change the fuel injection volume within the range of -12 and +12%. The injection volume can be changed in 1% graduations within the range.
    2. The A/F sensor is displayed as AFS B1 S1, and the HO2 sensor is displayed as O2S B1 S2.


    Result: 
    Tester Display (Sensor)
    		Voltage Variations
    		Proceed to
    AFS B1 S1 (A/F)
    		Alternates between more and less than 3.3 V
    		OK
    AFS B1 S1 (A/F)
    		Remains at more than 3.3 V
    		NG
    AFS B1 S1 (A/F)
    		Remains at less than 3.3 V
    		NG

    HINT:
    A normal HO2 sensor voltage (O2S B1 S2) reacts in accordance with increases and decreases in fuel injection volumes. When the A/F sensor voltage remains at either less than or more than 3.3 V despite the HO2 sensor indicating a normal reaction, the A/F sensor is malfunctioning.


    A087979E05



OK
REPLACE AIR FUEL RATIO SENSOR
NG

CHECK AND REPLACE EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO (INJECTOR, FUEL PRESSURE, GAS LEAKAGE IN EXHAUST SYSTEM, ETC.)