P0136
2AR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0136-P0139: Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)
DESCRIPTION
HINT
Sensor 2 refers to the sensor mounted behind the Three-Way Catalytic Converter (TWC) and located far from the engine assembly.
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 (Three-Way Catalytic Converter) is used. For the most efficient use of the TWC, the air-fuel ratio is 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 (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 is 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.
for Mexico Models
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, a DTC is stored.
2. Abnormal Voltage Output of Heated Oxygen (HO2) Sensor (DTC P0136)
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 below 0.21 V and does not increase to higher than 0.69 V during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormal and stores DTCs P0136.
3. Open or Short in Heated Oxygen (HO2) Sensor Circuit (DTCs P0137 or P0138)
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 stores DTC P0137. When the target air-fuel ratio is lean and the voltage output is 0.69 V or higher (rich) during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormally high, and stores DTC P0138.
HINT
DTC P0138 is also set if the HO2 sensor voltage output is higher 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 or P0137)
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.
- DTC P0136 indicates the deterioration of the HO2 sensor. The ECM stores the DTC by calculating the impedance of the sensor when the typical enabling conditions are satisfied (2 driving cycles).
- DTC P0137 indicates an open or short circuit in the HO2 sensor (2 driving cycles). The ECM stores the DTC when the impedance of the sensor exceeds the threshold of 15 kOhms.
5. Abnormal Voltage Output of Heated Oxygen (HO2) Sensor During Fuel-cut (DTC P0139)
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 response has deteriorated, illuminates the MIL and stores a DTC.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
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):
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 Output Voltage (High output voltage):
Heated Oxygen Sensor Impedance (Low):
Heated Oxygen Sensor Impedance (High):
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 and P0138
1. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation) [A].
2. Start the engine and warm it up until the ECT reaches 75°C (167°F) or higher [B].
3. With the transmission in 4th gear or higher, drive the vehicle at 60 to 120 km/h (40 to 75 mph) for 10 minutes or more [C].
4. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
5. Input the DTC: P0136, P0137 or P0138.
6. Check the DTC judgment result [D].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT
If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [C] and [D].
7. If the test result is UNKNOWN, enter the following menus: Powertrain / Engine and ECT / Trouble Code / Pending.
8. Read Pending DTCs.
HINT
If a pending DTC is output, the system is malfunctioning.
9. If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.
HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
P0139
1. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation) [A].
2. Start the engine and warm it up until the ECT reaches 75°C (167°F) or higher [B].
3. Drive the vehicle at 60 km/h (40 mph), and then decelerate the vehicle by releasing the accelerator pedal for 5 seconds or more to perform the fuel-cut [C].
4. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
5. Input the DTC: P0139.
6. Check the DTC judgment result [D].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT
If the judgment result shows INCOMPLETE or UNKNOWN, move the shift lever to 2 and then perform steps [C] through [D] again.
7. If the test result is UNKNOWN, enter the following menus: Powertrain / Engine and ECT / Trouble Code / Pending.
8. Read Pending DTCs.
HINT
If a pending DTC is output, the system is malfunctioning.
9. If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.
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 (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.
(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 and ECT / Active Test / Control the Injection Volume for A/F sensor.
(f) Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume.)
(g) Monitor the output voltages of the A/F and HO2 sensors (AFS Voltage B1 S1 and O2S B1 S2) 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 (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 and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS Voltage B1 S1 and O2S B1 S2; and then press the graph button on the Data List view.
NOTICE:
Inspect the fuses of circuits related to this system before performing the following inspection procedure.
HINT
Read freeze frame data using the Techstream. Freeze frame data records the engine condition 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.
PROCEDURE
1. READ OUTPUT DTC (DTC P0136, P0137, P0138 OR P0139)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read DTCs.
Result
D -- READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
C -- READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
B -- CHECK FOR EXHAUST GAS LEAK
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / O2S B1 S2.
(e) Allow the engine to idle.
(f) Read the Heated Oxygen (HO2) sensor output voltage while idling.
Result
B -- PERFORM ACTIVE TEST USING TECHSTREAM (INJECTION VOLUME)
A -- Continue to next step.
3. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)
(a) Disconnect the heated oxygen sensor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
(c) Reconnect the heated oxygen sensor connector.
NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)
(a) Turn the ignition 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:
(d) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM Removal
5. PERFORM ACTIVE TEST USING TECHSTREAM (INJECTION VOLUME)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Start the engine and warm it up.
(e) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.
(f) Change the fuel injection volume using the Techstream, and monitor the voltage output of the Air Fuel Ratio (A/F) and Heated Oxygen (HO2) 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 1% graduations within the range.
- The A/F sensor is displayed as AFS Voltage B1 S1, and the HO2 sensor is displayed as O2S B1 S2 on the Techstream.
Result
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 below or higher 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 -- Continue to next step.
6. INSPECT AIR FUEL RATIO SENSOR
HINT
This A/F sensor test is to check the A/F sensor current during fuel-cut. When the sensor is normal, the sensor current indicates below 3.0 mA in this test.
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Drive the vehicle according to the drive pattern listed below:
(1) Warm up the engine until the engine coolant temperature reaches 75°C (167°F) or higher.
(2) Drive the vehicle at 60 km/h (40 mph) or more and decelerate the vehicle for 5 seconds or more.
(3) Repeat the step above at least 3 times.
(e) Enter the following menus: Powertrain / Engine and ECT / Monitor / O2 Sensor / Details.
(f) Confirm that RANGE B1S1 is either PASS or FAIL. If the Techstream shows incomplete, recheck RANGE B1S1 after performing the drive pattern.
(g) Select the RANGE B1S1.
(h) Read the test value.
Standard current:
Below 3.0 mA
HINT
If the Techstream shows incomplete again, accelerate the vehicle and use second gear to decelerate the vehicle. Refer to the Confirmation Driving Pattern.
NG -- REPLACE AIR FUEL RATIO SENSOR
OK -- REPLACE HEATED OXYGEN SENSOR
7. READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
(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 and ECT / Active Test / Injection Volume.
(e) Change the fuel injection volume using the Techstream, monitoring the voltage output of HO2 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 1% graduations within the range.
Standard:
Fluctuates between 0.4 V or less and 0.5 V or higher.
NG -- CHECK FOR EXHAUST GAS LEAK
OK -- Continue to next step.
8. PERFORM ACTIVE TEST USING TECHSTREAM (INJECTION VOLUME)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Start the engine and warm it up.
(e) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.
(f) Change the fuel injection volume using the Techstream, and monitor the voltage output of the Air Fuel Ratio (A/F) and Heated Oxygen (HO2) 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 1% graduations within the range.
- The A/F sensor is displayed as AFS Voltage B1 S1, and the HO2 sensor is displayed as O2S B1 S2 on the Techstream.
Result
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 below or higher 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 EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO AND REPAIR CAUSE (FUEL INJECTOR, FUEL PRESSURE, GAS LEAK FROM SYSTEM, ETC.)
9. CHECK FOR EXHAUST GAS LEAK
(a) Check for exhaust gas leaks.
OK:
No gas leak.
NG -- REPAIR OR REPLACE EXHAUST GAS LEAK POINT
OK -- Continue to next step.
10. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE) P0037
NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.
11. 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):
Standard Resistance (Check for short):
(d) Reconnect the heated oxygen sensor connector.
(e) 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 Removal.
NEXT -- Continue to next step.
13. PERFORM CONFIRMATION DRIVING PATTERN
HINT
Refer to the Confirmation Driving Pattern.
NEXT -- Continue to next step.
14. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137 OR P0138)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
(e) Input DTCs: P0136, P0137 and P0138.
Check that the DTC MONITOR is NORMAL. If the DTC MONITOR is INCOMPLETE, perform the drive pattern increasing the vehicle speed and using second gear to decelerate the vehicle.
Result
B -- REPLACE AIR FUEL RATIO SENSOR Removal
A -- END
15. REPLACE AIR FUEL RATIO SENSOR
(a) Replace the air fuel ratio sensor Removal.
NEXT -- Continue to next step.
16. PERFORM CONFIRMATION DRIVING PATTERN
HINT
Refer to the Confirmation Driving Pattern.
NEXT -- Continue to next step.
17. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136 OR P0138)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
(e) Input DTCs: P0136 and P0138.
Check that the DTC MONITOR is NORMAL. If the DTC MONITOR is INCOMPLETE, perform the drive pattern increasing the vehicle speed and using second gear to decelerate the vehicle.
Result
B -- REPLACE HEATED OXYGEN SENSOR Removal
A -- END
18. READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / O2S B1 S2.
(e) Allow the engine to idle.
(f) Read the Heated Oxygen (HO2) sensor output voltage while idling.
Result
B -- PERFORM CONFIRMATION DRIVING PATTERN
A -- Continue to next step.
19. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)
(a) Disconnect the heated oxygen sensor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
(c) Reconnect the heated oxygen sensor connector.
NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.
20. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)
(a) Turn the ignition 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:
(d) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM Removal
21. PERFORM CONFIRMATION DRIVING PATTERN
HINT
Refer to the CONFIRMATION DRIVING PATTERN.
NEXT -- Continue to next step.
22. READ DTC OUTPUT (DTC P0139 IS OUTPUT AGAIN)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
(e) Input DTCs: P0139.
Check that the DTC MONITOR is NORMAL. If the DTC MONITOR is INCOMPLETE, perform the drive pattern increasing the vehicle speed and using second gear to decelerate the vehicle.
Result
B -- CHECK INTERMITTENT PROBLEMS Check for Intermittent Problems
A -- REPLACE HEATED OXYGEN SENSOR Removal