Part 1
1GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0136-P0139,P0156-P0159: Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)
CAUTION / NOTICE / HINT
DESCRIPTION
Sensor 2 refers to the sensor mounted behind the three way catalytic converter and located far from the engine assembly.
A three way catalytic converter is used in order to convert the carbon monoxide, hydrocarbons, and nitrogen oxides, into less harmful substances. To allow the three way catalytic converter to function effectively, it is necessary to keep the air fuel ratio of the engine near the stoichiometric air fuel ratio. 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 three way catalytic converter, 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 great. The heated oxygen sensor informs the ECM that the post-three way catalytic converter 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 small. The heated oxygen sensor informs the ECM that the post-three way catalytic converter 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 three way catalytic converter 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.
For Mexico Models
MONITOR DESCRIPTION
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 and heated oxygen sensor functions (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.
Abnormal Voltage Output of Heated Oxygen sensor (DTC 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 heated oxygen 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 stores DTC P0136 or P0156.
Open or Short in Heated Oxygen Sensor Circuit (DTC P0137 and P0157 or P0138 and P0158)
During active air-fuel ratio control, the ECM calculates the oxygen storage capacity* of the three-way catalytic converter by forcibly regulating the air-fuel ratio to become rich or lean. If the heated oxygen sensor has an open or short, or the voltage output of the sensor decreases significantly, the oxygen storage capacity 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 or P0157. When the target air-fuel ratio is lean and the voltage output is more than 0.59 V (rich) during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormally high, and stores DTC P0138 or P0158.
HINT
DTC P0138 or P0158 is also stored if the heated oxygen sensor voltage output is 1.2 V or more for 10 seconds or more.
*: The three-way catalytic converter has the capability to store oxygen. The oxygen storage capacity and the emission purification capacity of the three-way catalytic converter are mutually related. The ECM determines whether the catalyst has deteriorated based on the calculated oxygen storage capacity value P0420.
High or Low Impedance of Heated Oxygen Sensor (DTC 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 variations in 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 and P0156 indicate the deterioration of the heated oxygen sensor. The ECM sets this DTC by calculating the impedance of the sensor when the typical enabling conditions are satisfied (2 driving cycles).
* DTC P0137 and P0157 indicate an open or short circuit in the heated oxygen sensor (2 driving cycles). The ECM sets this DTC when the impedance of the sensor exceeds the threshold 15 kOhms.
Heated Oxygen sensor output voltage during fuel cut (P0139 or P0159)
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's response feature has deteriorated, illuminates the MIL and sets a DTC.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All
Heated Oxygen Sensor Output Voltage (Abnormal Voltage Output, 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 Output Voltage During Fuel Cut
TYPICAL MALFUNCTION THRESHOLDS
Heated Oxygen Sensor Output Voltage (Abnormal Voltage Output)
Heated Oxygen Sensor Output Voltage (Low)
Heated Oxygen Sensor Output Voltage (High)
Heated Oxygen Sensor Impedance (Low)
Heated Oxygen Sensor Impedance (High)
Heated Oxygen Sensor Output Voltage (Extremely High)
Heated Oxygen Sensor Output Voltage During Fuel Cut
COMPONENT OPERATING RANGE
MONITOR RESULT
Refer to CHECKING MONITOR STATUS Mode 6 Data.
CONFIRMATION DRIVING PATTERN
P0136, P0137, P0138, P0156, P0157 and P0158
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).
4. Turn the ignition switch off and wait for at least 30 seconds.
5. Turn the ignition switch to ON and turn the Techstream on [A].
6. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [B].
7. With the transmission in 4th gear or higher, drive the vehicle at 60 to 120 km/h (37 to 75 mph) for 10 minutes or more [C].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
8. Enter the following menus: Powertrain / Engine and ECT/ Trouble Codes [D].
9. Read pending DTCs.
HINT
* If a pending DTC is output, the system is malfunctioning.
* If a pending DTC is not output, perform the following procedure.
10. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
11. Input the DTC: P0136, P0137, P0138, P0156, P0157, or P0158.
12. 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 UNKNOWN, perform steps [C] through [D].
13. If 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 and P0159
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).
4. Turn the ignition switch off and wait for at least 30 seconds.
5. Turn the ignition switch to ON and turn the Techstream on [A].
6. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [B].
7. Drive the vehicle at 60 km/h (40 mph), and then decelerate the vehicle by releasing the accelerator pedal for 7 seconds or more to perform the fuel-cut [C].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
9. Read the 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.
10. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
11. Input the DTC: P0139 or P0159.
12. 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 UNKNOWN, shift the transmission to 2nd gear, and then perform steps [C] and [D] again.
13. If 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 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. Start the engine and turn the Techstream on.
3. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.
5. Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
6. Monitor the output voltages of the air fuel ratio sensor and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) 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.
* Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Standard voltage:
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 / AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2; 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
* Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.
* Sensor 1 refers to the sensor closest to the engine assembly.
* Sensor 2 refers to the sensor farthest away from the engine assembly.
* If the OX1B wire from the ECM connector is short-circuited to the +B wire, DTC P0136 will be stored.
* If the OX2B wire from the ECM connector is short-circuited to the +B wire, DTC P0156 will be stored.
PROCEDURE
1. READ DTC OUTPUT (DTC P0136, P0137, P0138, P0139, P0156, P0157, P0158 AND P0159)
(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
HINT
HINT: If any DTCs other than P0136, P0137, P0138, P0156, P0157 or P0158 are output, troubleshoot those DTCs first.
E -- GO TO DTC CHART SFI System
D -- CHECK FOR EXHAUST GAS LEAK
C -- PERFORM ACTIVE TEST USING TECHSTREAM
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 / O2S B1S2 or O2S B2S2.
(e) Allow the engine to idle.
(f) Read the heated oxygen sensor output voltage while idling.
Result
NG -- PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)
OK -- 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:
Text in Illustration
(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.
(b) Disconnect the ECM connectors.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
(d) Reconnect the ECM connectors.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
5. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)
(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.
(e) Change the fuel injection volume using the Techstream and monitor the voltage output of the 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 or AFS Voltage B2S1, and the heated oxygen sensor is displayed as O2S B1S2 or O2S B2S2 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.
Result
HINT
A normal heated oxygen sensor voltage (O2S B1S2 or O2S B2S2) reacts in accordance with increases and decreases in fuel injection volumes. When the air fuel ratio sensor voltage remains at either below 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.