СИСТЕМА SFI, Diagnostic DTC:P0136, P0137, P0138
| DTC Code | DTC Name |
|---|---|
| P0136 | Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2) |
| P0137 | Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2) |
| P0138 | Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2) |
CAUTION / NOTICE / HINT
Tech Tips
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.
| DTC No. | DTC Detection Conditions | Trouble Areas |
|---|---|---|
| P0136 |
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
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) |
|
| P0137 |
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
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) |
|
| P0138 |
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
Heated oxygen sensor output voltage exceeds 1.2 V for more than 10 seconds (1 trip detection logic) |
|
WIRING DIAGRAM
CONFIRMATION DRIVING PATTERN
Tech Tips
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This confirmation driving pattern is used in the following diagnostic troubleshooting inspection procedure when using the intelligent tester.
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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.
(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.
Tech Tips
If a malfunction exists, the MIL will illuminate during step (g).
Note
If the conditions in this test are not strictly followed, detection of a malfunction will not occur.
INSPECTION PROCEDURE
Tech Tips
Intelligent tester only:
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 (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" operation using intelligent tester.
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Connect the intelligent tester to the DLC3.
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Start the engine and turn the tester ON.
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Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
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On the tester, select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.
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Perform the "Control the Injection Volume" operation with the engine in an idling condition (press the right or left button to change the fuel injection volume).
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Monitor the output voltage of the A/F and Heated oxygen sensors (AFS B1 S1 and O2S B1 S2) displayed on the tester.
Tech Tips
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The "Control the Injection Volume" operation lowers the fuel injection volume by 12.5% or increases the injection volume by 24.8%.
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Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
| Standard | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Note
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 +24.8% -12.5% |
 |
Injection Volume +24.8% -12.5% |
|
- |
| Output Voltage More than 3.35 V Less than 3.0 V |
 |
Output Voltage More than 0.55 V Less than 0.4 V |
 |
||
| 2 | Injection Volume +24.8% -12.5% |
|
Injection Volume +24.8% -12.5% |
|
|
| Output Voltage Almost no reaction |
 |
Output Voltage More than 0.55 V Less than 0.4 V |
|
||
| 3 | Injection Volume +24.8% -12.5% |
|
Injection Volume +24.8% -12.5% |
|
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| Output Voltage More than 3.35 V Less than 3.0 V |
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Output Voltage Almost no reaction |
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||
| 4 | Injection volume +24.8% -12.5% |
|
Injection Volume +24.8% -12.5% |
|
|
| Output Voltage Almost no reaction |
|
Output Voltage Almost no reaction |
|
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The following "Control the Injection Volume" 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.
Tech Tips
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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.
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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.
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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.
PROCEDURE
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CHECK OTHER DTC OUTPUT
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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 Tech Tips
If any codes besides P0136, P0137 and / or P0138 are output, perform the troubleshooting for those codes first.
B 
CHECK INTEGRATION NO.1 RELAY (MAIN RELAY) Click here
C
READ VALUE USING DATA LIST Click here
A 
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READ VALUE USING DATA LIST
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Connect the intelligent tester to the DLC3.
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Turn the ignition switch ON and turn the intelligent tester ON.
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Enter the following menus: Powertrain / Engine and ECT / Data List / O2S B1 S2.
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Run the engine at idle.
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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
PERFORM CONFIRMATION DRIVING PATTERN Click here
A
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CHECK WIRE HARNESS (FOR SHORT)
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Turn the ignition switch OFF and wait for 5 minutes.
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Disconnect the E12 ECM connector.
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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
-
-
INSPECT HEATED OXYGEN SENSOR (FOR SHORT)
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Disconnect the H7 sensor connector.
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Measure the resistance of the sensor.
Standard resistance Tester Connection Specified Condition 2 (+B) - 4 (E2) 10 kΩ or higher 2 (+B) - 3 (OX1B) 10 kΩ or higher
OK
REPAIR OR REPLACE HARNESS AND CONNECTOR
NG 
REPLACE HEATED OXYGEN SENSOR
-
-
PERFORM CONFIRMATION DRIVING PATTERN
NEXT
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READ OUTPUT DTC (CHECK MODE)
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Change the ECM to check mode with the intelligent tester. Enter the following menus: Powertrain / Engine and ECT / Check Mode.
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Warm up the engine and drive the vehicle at over 40 km/h (25 mph) for an accumulated total of 10 minutes.
Tech Tips
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.
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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
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-
READ VALUE USING DATA LIST
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After warming up the engine, run the engine at 2,500 rpm for 3 minutes.
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Read the output voltage of the heated oxygen sensor when the engine rpm is suddenly increased.
Tech Tips
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
PERFORM CONFIRMATION DRIVING PATTERN Click here
NG
-
-
CHECK FOR EXHAUST GAS LEAKAGE
OK No gas leakage.
NG
REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK
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INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
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Disconnect the H7 sensor connector.
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Measure the resistance of the sensor.
Standard resistance Tester Connection Condition Specified Condition 2 (+B) -1 (HT1B) 20°C (68°F) 11 to 16 Ω 1 (HT1B) - 4 (E2) Always 10 kΩ or higher
NG
REPLACE HEATED OXYGEN SENSOR
OK
-
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CHECK INTEGRATION NO.1 RELAY (MAIN RELAY)
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Remove the integration relay from the engine room junction block.
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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 NO.1 RELAY
OK
-
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CHECK WIRE HARNESS (HEATED OXYGEN SENSOR - ECM)
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Disconnect the H7 heated oxygen sensor connector.
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Disconnect the E12 ECM connector.
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Measure the resistance of the wire harness side connectors.
Standard resistance Tester Connection Specified Condition H7-1 (HT1B) - E12-2 (HT1B)
H7-3 (OX1B) - E12-25 (OX1B)
Below 1 Ω H7-1 (HT1B) - E12-2 (HT1B) - Body ground
H7-3 (OX1B) - E12-25 (OX1B) - Body ground
10 kΩ or higher 
NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK
REPLACE HEATED OXYGEN SENSOR
-
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PERFORM CONFIRMATION DRIVING PATTERN
Tech Tips
Clear all DTCs prior to performing the confirmation driving pattern.
NEXT
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READ OUTPUT DTC (DTC P0136 IS OUTPUT AGAIN)
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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
-
-
REPLACE HEATED OXYGEN SENSOR
NEXT
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PERFORM CONFIRMATION DRIVING PATTERN
Tech Tips
Clear all DTCs prior to performing the confirmation driving pattern.
NEXT
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READ OUTPUT DTC (DTC P0136 IS OUTPUT AGAIN)
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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
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PERFORM ACTIVE TEST (INJECTOR VOLUME)
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Start the engine and warm it up.
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Connect the intelligent tester to the DLC3.
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Turn ON the ignition switch and the intelligent tester main switch.
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Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.
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Using the intelligent tester, change the injection volume to check the A/F sensor output and heated oxygen sensor output values below.
Tech Tips
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Change the fuel injection volume within the range of -12 and +12%. The injection volume can be changed in 1% graduations within the range.
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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 Tech Tips
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.
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OK
REPLACE AIR FUEL RATIO SENSOR
NG
CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO AND REPAIR CAUSE (INJECTOR, FUEL PRESSURE, GAS LEAKAGE IN EXHAUST SYSTEM, ETC.)
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