Part 1
2ZR-FXE ENGINE CONTROL: SFI SYSTEM: P0136-P0139: Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)
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 (Three-Way Catalytic Converter) 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. For the purpose of helping 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 high. 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 is low. 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 duration 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.
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 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 sensor malfunctions (refer to the diagram below).
Active air fuel ratio control is performed for approximately 30 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 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 heated oxygen sensor voltage does not increase to 0.59 V or higher during active air fuel ratio control, the ECM determines that the sensor voltage output is abnormal and stores DTCs P0136.
3. Open in Heated Oxygen Sensor Circuit (DTC P0137)
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 heated oxygen sensor has an open 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 heated oxygen sensor output does not change.
While performing active air fuel ratio control, when the target air fuel ratio is rich and the heated oxygen sensor voltage output is less than 0.21 V (lean), the ECM interprets this as an abnormally low sensor output voltage and stores DTC P0137.
HINT
*: 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 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 heated oxygen 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 heated oxygen 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 heated oxygen sensor (2 driving cycles). The ECM stores the DTC when the impedance of the sensor exceeds the threshold 15 kOhms.
5. Extremely High Output Voltage of Heated Oxygen Sensor (DTC P0138)
The ECM continuously monitors the heated oxygen sensor output voltage while the engine is running.
DTC P0138 is stored if the heated oxygen sensor voltage output is 1.2 V or higher for 10 seconds or more.
6. Abnormal Voltage Output of Heated Oxygen Sensor During Fuel-cut (DTC P0139)
The sensor output voltage drops to less than 0.2 V (extremely lean status) immediately when the vehicle decelerates and fuel cut is operating. If the voltage does not drop to less than 0.2 V for 6 seconds or more, or voltage does not drop from 0.35 to 0.2 V for 1 second or more, the ECM determines that the sensor response has deteriorated, illuminates the MIL and stores a DTC.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All
P0136 and P0137: Heated Oxygen Sensor Output Voltage (Voltage Check and Low Voltage)
P0136: Heated Oxygen Sensor Impedance (Low Impedance)
P0137: Heated Oxygen Sensor Impedance (High Impedance)
P0138: Heated Oxygen Sensor Output Voltage (Extremely High)
P0139: Heated Oxygen Sensor Voltage During Fuel-cut
TYPICAL MALFUNCTION THRESHOLDS
P0136: Heated Oxygen Sensor Output Voltage (Voltage Check)
P0137: Heated Oxygen Sensor Output Voltage (Low Voltage)
P0136: Heated Oxygen Sensor Impedance (Low Impedance)
P0137: Heated Oxygen Sensor Impedance (High Impedance)
P0138: Heated Oxygen Sensor Output Voltage (Extremely High)
P0139: Heated Oxygen Sensor Voltage During Fuel-cut
MONITOR RESULT
Refer to Checking Monitor Status Mode 6 Data.
CONFIRMATION DRIVING PATTERN
HINT
* This confirmation driving pattern is used in the "Perform Confirmation Driving Pattern" procedure of the following diagnostic troubleshooting procedure.
* Performing this confirmation driving 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.
P0136, P0137 and P0138
1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG) and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
4. Turn the power switch off and wait for at least 30 seconds.
5. Turn the power switch on (IG) and turn the Techstream on [A].
6. Put the engine in inspection mode (maintenance mode) Component Tests and General Diagnostics.
7. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [B].
8. With the shift lever in D, drive the vehicle at 75 to 120 km/h (47 to 75 mph) for 10 minutes or more [C].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
10. Read the pending DTCs.
HINT
* If a pending DTC is output, the system is malfunctioning.
* If a pending DTC is not output, perform the following procedure.
11. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
12. Input the DTC: P0136, P0137 or P0138.
13. Check the DTC judgment result.
HINT
* If the judgment result shows NORMAL, the system is normal.
* If the judgment result shows ABNORMAL, the system has a malfunction.
* If the judgment result shows INCOMPLETE or N/A, perform steps [C] and [D] again.
14. If no pending DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.
HINT
* If a permanent DTC is output, the system is malfunctioning.
* If no permanent DTC is output, the system is normal.
P0139
1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG) and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
4. Turn the power switch off and wait for at least 30 seconds.
5. Turn the power switch on (IG) and turn the Techstream on [A].
6. Put the engine in inspection mode (maintenance mode) Component Tests and General Diagnostics.
7. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [B].
8. Drive the vehicle at 75 km/h (47 mph), and then decelerate the vehicle by releasing the accelerator pedal for 5 seconds or more to perform the fuel-cut [C].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
10. Read the pending DTCs.
HINT
* If a pending DTC or current DTC is output, the system is malfunctioning.
* If a pending DTC or current DTC is not output, perform the following procedure.
11. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
12. Input the DTC: P0139.
13. Check the DTC judgment result.
HINT
* If the judgment result shows NORMAL, the system is normal.
* If the judgment result shows ABNORMAL, the system has a malfunction.
* If the judgment result shows INCOMPLETE or N/A, drive the vehicle with the shift lever in B position, and then perform steps [C] and [D] again.
14. If no pending DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.
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 function provided in the Active Test. The Control the Injection Volume function can help to determine whether the air fuel ratio sensor, heated oxygen sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the Control the Injection Volume operation using the Techstream.
1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Put the engine in inspection mode (maintenance mode) Component Tests and General Diagnostics.
5. Start the engine.
6. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
HINT
During charging control, the engine speed is set at idle. Therefore, the engine speed does not increase when depressing the accelerator pedal. In this case, warm up the engine after charging control has completed.
7. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume / Gas AF Control / AFS Voltage B1S1 and O2S B1S2.
8. Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
9. Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.
HINT
* Change the fuel injection volume within the range of -12% to +12%. The injection volume can be changed in fine gradations.
* Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
NOTICE:
The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
- Following the Control the Injection Volume procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
- To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume / Gas AF Control / AFS Voltage B1S1 and O2S B1S2; and then press the graph button on the Data List view.
NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.
HINT
* Sensor 1 refers to the sensor closest to the engine assembly.
* Sensor 2 refers to the sensor farthest away from the engine assembly.
* 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 power switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read the DTCs.
Result:
HINT
If any DTCs other than P0136, P0137, P0138 or P0139 are output, troubleshoot those DTCs first.
B -- CHECK EXHAUST GAS LEAK
C -- PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)
D -- CHECK FOR EXHAUST GAS LEAK
E -- GO TO DTC CHART SFI System
A -- Continue to next step.
2. 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:
Text in Illustration
NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)
(a) Turn the power 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 (Check for Short):
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
4. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Put the engine in inspection mode (maintenance mode) Component Tests and General Diagnostics.
(e) Start the engine and warm it up.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume / Gas AF Control / O2S B1S2.
(g) Change the fuel injection volume using the Techstream, and monitor the voltage output of heated oxygen sensor displayed on the Techstream.
HINT
* Change the fuel injection volume within the range of -12% to +12%. The injection volume can be changed in fine gradations within this range.
* The heated oxygen sensor has a maximum output delay of approximately 20 seconds.
Standard voltage:
Fluctuates between 0.4 V or less, and 0.55 V or higher.
NG -- CHECK EXHAUST GAS LEAK
OK -- Continue to next step.
5. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Put the engine in inspection mode (maintenance mode) Component Tests and General Diagnostics.
(e) Start the engine and warm it up.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume / Gas AF Control / AFS Voltage B1S1 and O2S B1S2.
(g) Change the fuel injection volume using the Techstream, and monitor the voltage output of air fuel ratio and heated oxygen 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 fine gradations within this range.
* The air fuel ratio sensor is displayed as AFS Voltage B1S1, and the heated oxygen sensor is displayed as O2S B1S2 on the Techstream.
* The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
* If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.
Result
HINT
A normal heated oxygen sensor voltage (O2S B1S2) reacts in accordance with increases and decreases in fuel injection volumes. When the air fuel ratio sensor voltage (AFS Voltage B1S1) remains at either less or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.
NG -- REPLACE AIR FUEL RATIO SENSOR
OK -- Continue to next step.
6. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Put the engine in inspection mode (maintenance mode) Component Tests and General Diagnostics.
(e) Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or more.
HINT
The A/C switch and all accessory switches should be off.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.
(g) Check the engine idling condition and MAP values in the Data List while performing the Active Test.
HINT
* Do not leave the EGR valve open for 10 seconds or more during the Active Test.
* Be sure to return the EGR valve to step 0 when the Active Test is completed.
* Do not open the EGR valve 30 steps or more during the Active Test.
OK:
MAP and idling condition change in response to EGR step position.
Standard:
HINT
During Active Test, if the idling condition does not change in response to EGR step position, then there is probably a malfunction in the EGR valve.
NG -- INSPECT EGR VALVE ASSEMBLY
OK -- CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO AND REPAIR CAUSE (FUEL INJECTOR ASSEMBLY, FUEL PRESSURE, GAS LEAK FROM SYSTEM)
7. INSPECT EGR VALVE ASSEMBLY
(a) Remove the EGR valve assembly Removal.
(b) Check if the EGR valve is stuck open.
OK:
EGR valve is tightly closed.
NG -- REPLACE EGR VALVE ASSEMBLY Removal
OK -- CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO AND REPAIR CAUSE (FUEL INJECTOR ASSEMBLY, FUEL PRESSURE, GAS LEAK FROM SYSTEM)
8. CHECK EXHAUST GAS LEAK
(a) Check for exhaust gas leakage.
OK:
No gas leaks.
NG -- REPAIR OR REPLACE EXHAUST GAS LEAK POINT
OK -- Continue to next step.
9. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
(a) Inspect the heated oxygen sensor Heated Oxygen Sensor.
NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.
10. 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):
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.