SFI SYSTEM, Diagnostic DTC:P0136,P0137 and 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) |
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.
DTC No. |
Detection Item |
DTC Detection Condition |
Trouble Area |
MIL |
Memory |
|---|---|---|---|---|---|
P0136 |
Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2) |
Abnormal voltage output: During active air fuel ratio control, the following conditions (a) and (b) are met for a certain period of time (2 trip detection logic):
|
|
Comes on |
DTC stored |
P0137 |
Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2) |
Low voltage (open): During active air fuel ratio control, the following conditions (a) and (b) are met for a certain period of time (2 trip detection logic):
|
|
Comes on |
DTC stored |
P0138 |
Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2) |
High voltage (short): During active air fuel ratio control, the following conditions (a) and (b) are met for a certain period of time (2 trip detection logic):
|
|
Comes on |
DTC stored |
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 (TWC) and heated oxygen 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.
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 decrease to less than 0.21 V and does not increase to 0.69 V or higher during active air fuel ratio control, the ECM determines that the sensor voltage output is abnormal and stores DTC P0136.
Open or Short in Heated Oxygen Sensor Circuit (DTC 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 heated oxygen sensor has an open or short circuit, or the voltage output of the sensor noticeably decreases, the OSC indicated 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. When the target air fuel ratio is lean and the voltage output is higher than 0.69 V (rich) during active air fuel ratio control, the ECM determines that the sensor voltage output is abnormally high and stores DTC P0138.
*: The TWC has the capability to store oxygen. The OSC and the emissions purification capacity of the TWC are mutually related. The ECM determines whether the catalyst has deteriorated based on the calculated OSC value.
MONITOR STRATEGY
Required Sensors/Components (Main) |
Heated oxygen sensor (sensor 2) |
Required Sensors/Components (Related) |
Crankshaft position sensor Engine coolant temperature sensor Mass air flow meter sub-assembly Throttle position sensor Air fuel ratio sensor |
Frequency of Operation |
Once per driving cycle |
TYPICAL ENABLING CONDITIONS
Active air fuel ratio control |
Executing |
Active air fuel ratio control begins when all of the following conditions are met: |
- |
Battery voltage |
11 V or higher |
Engine coolant temperature |
75°C (167°F) or higher |
Idling |
Off |
Engine speed |
Less than 4000 rpm |
Air fuel ratio sensor status |
Activated |
Fuel system status |
Closed loop |
Engine load |
10% or higher, and less than 80% |
TYPICAL MALFUNCTION THRESHOLDS
Either of the following conditions is met |
1 or 2 |
1. Both of the following conditions are met |
(a) and (b) |
(a) Commanded air fuel ratio |
14.3 or less |
(b) Heated oxygen sensor voltage |
0.21 V or higher, and less than 0.69 V |
2. Both of the following conditions are met |
(c) and (d) |
(c) Commanded air fuel ratio |
14.9 or more |
(d) Heated oxygen sensor voltage |
0.21 V or higher, and less than 0.69 V |
Both of the following conditions are met |
(a) and (b) |
(a) Commanded air fuel ratio |
14.3 or less |
(b) Heated oxygen sensor voltage |
Less than 0.21 V |
Both of the following conditions are met |
(a) and (b) |
(a) Commanded air fuel ratio |
14.9 or more |
(b) Heated oxygen sensor voltage |
Higher than 0.69 V |
CONFIRMATION DRIVING PATTERN
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.
Connect the GTS to the DLC3.
Turn the ignition switch to ON and turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the GTS on [A].
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [B].
With the transaxle in 4th gear or more, drive the vehicle at 70 to 100 km/h (43 to 62 mph) for 10 minutes or more [C].
CAUTION:When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].
Read the pending DTCs.
Tip:If a pending DTC is output, the system is malfunctioning.
If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0136, P0137 or P0138.
Check the DTC judgment result.
GTS Display
Description
NORMAL
DTC judgment completed
System normal
ABNORMAL
DTC judgment completed
System abnormal
INCOMPLETE
DTC judgment not completed
Perform driving pattern after confirming DTC enabling conditions
N/A
Unable to perform DTC judgment
Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
Tip: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.
WIRING DIAGRAM
Refer to DTC P0037.
CAUTION / NOTICE / 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 sensor, heated oxygen 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 GTS.
Connect the GTS to the DLC3.
Start the engine.
Turn the GTS on.
Warm up the engine and run the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / All Data / AFS Voltage B1S1 and O2S B1S2.
Perform the Active Test operation with the engine idling (press the 12.5% or -12.5% button to change the fuel injection volume).
Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the GTS.
The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
GTS Display (Sensor) |
Injection Volume |
Status |
Voltage |
|---|---|---|---|
AFS Voltage B1S1 (Air fuel ratio) |
12.5% |
Rich |
Below 3.1 V |
-12.5% |
Lean |
Higher than 3.4 V |
|
O2S B1S2 (Heated oxygen) |
12.5% |
Rich |
Higher than 0.55 V |
-12.5% |
Lean |
Below 0.4 V |
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 for A/F Sensor 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 for A/F Sensor / All Data / AFS Voltage B1S1 and O2S B1S2; then press the view button.
Inspect the fuses for circuits related to this system before performing the following procedure.
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 GTS. 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.
PROCEDURE
READ OUTPUT DTC (DTC P0136, P0137 OR P0138)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Read the DTCs.
Powertrain > Engine and ECT > Trouble Codes
Result
Result
Proceed to
DTC P0138 is output
A
DTC P0137 is output
B
DTC P0136 is output
C
DTC P0136, P0137 or P0138 and other DTCs are output
D
Tip:If any DTCs other than P0136, P0137 and P0138 are output, troubleshoot those DTCs first.
B CHECK FOR EXHAUST GAS LEAKClick here
C PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)Click here
READ VALUE USING GTS (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Start the engine.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / O2S B1S2.
Powertrain > Engine and ECT > Data List
Tester Display
O2S B1S2
Allow the engine to idle.
Read the heated oxygen sensor output voltage while idling.
Result
Heated Oxygen Sensor Output Voltage
Proceed to
1.0 V or higher
A
Less than 1.0 V
B
B PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)Click here
INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)
-
*a
Component without harness connected
(Heated Oxygen Sensor)
Disconnect the heated oxygen sensor connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection
Condition
Specified Condition
2 (+B) - 3 (OX1B)
Always
10 kΩ or higher
2 (+B) - 4 (E2)
Always
10 kΩ or higher
Result
Proceed to
OK
NG
-
CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)
Turn the ignition switch off and wait for 5 minutes or more.
Disconnect the ECM connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection
Condition
Specified Condition
B31-22 (HT1B) - B31-103 (OX1B)
Always
10 kΩ or higher
Result
Proceed to
OK
NG
NG REPAIR OR REPLACE HARNESS OR CONNECTOR
PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Start the engine.
Warm up the engine.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / All Data / AFS Voltage B1S1 and O2S B1S2.
Powertrain > Engine and ECT > Active Test
Active Test Display
Control the Injection Volume for A/F Sensor
Data List Display
AFS Voltage B1S1
O2S B1S2
Change the fuel injection volume using the GTS, and monitor the voltage output of the air fuel ratio sensor and heated oxygen sensor displayed on the GTS.
Tip:The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
The air fuel ratio sensor is displayed as AFS Voltage B1S1, and the heated oxygen sensor is displayed as O2S B1S2 on the GTS.
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
GTS Display (Sensor)
Voltage Variation
Proceed to
AFS Voltage B1S1 (Air fuel ratio)
Alternates between higher than and less than 3.3 V
OK
Remains at higher than 3.3 V
NG
Remains at less than 3.3 V
Tip: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 SENSORClick here
INSPECT AIR FUEL RATIO SENSOR
Tip:This air fuel ratio sensor test is to check the air fuel ratio sensor current during the fuel-cut operation. When the sensor is normal, the sensor current will indicate below 2.2 mA in this test.
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Clear the DTCs.
Powertrain > Engine and ECT > Clear DTCs
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.
Drive the vehicle at 60 km/h (37 mph) or more for 10 minutes or more.
CAUTION:When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Stop the vehicle.
Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / AFS Current B1S1.
Powertrain > Engine and ECT > Data List
Tester Display
AFS Current B1S1
Drive the vehicle at 60 km/h (37 mph) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times.
CAUTION:When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Read the value of the air fuel ratio sensor current while the fuel-cut operation is being performed.
Standard Current
Less than 2.2 mA
Tip:To measure the air fuel ratio sensor current precisely, perform the fuel-cut operation as long as possible.
If it is difficult to measure the air fuel ratio sensor current, use the snapshot function of the GTS.
Result
Proceed to
OK
NG
OK REPLACE HEATED OXYGEN SENSORClick here
NG REPLACE AIR FUEL RATIO SENSORClick here
REPLACE AIR FUEL RATIO SENSOR
Replace the air fuel ratio sensor.
Result
Proceed to
NEXT
PERFORM CONFIRMATION DRIVING PATTERN
Perform Confirmation Driving Pattern.
Result
Proceed to
NEXT
CHECK WHETHER DTC OUTPUT RECURS (DTC P0136 OR P0138)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Powertrain > Engine and ECT > Utility
Tester Display
All Readiness
Input the DTC: P0136 or P0138.
Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again but increase the vehicle speed.
Result
Result
Proceed to
ABNORMAL
(DTC P0136 or P0138 is output)
A
NORMAL
(DTC is not output)
B
B END
PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or more.
Tip:The A/C switch and all accessory switches should be off.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / All Data / MAP and Throttle Idle Position.
Powertrain > Engine and ECT > Active Test
Active Test Display
Control the EGR Step Position
Data List Display
MAP
Throttle Idle Position
Confirm that the Throttle Idle Position is ON and check the engine idling condition and MAP values in the Data List while performing the Active Test.
OK
MAP and idling condition change in response to EGR step position.
-
EGR Step Position (Active Test)
0 Steps
0 to 30 Steps
Idling condition
Steady idling
Idling changes from steady to rough idling or engine stalls
MAP
(Data List)
MAP value is 20 to 48 kPa(abs)
[150 to 360 mmHg(abs)]
(EGR valve is fully closed)
MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed
Tip: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.
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 assembly.
Result
Result
Proceed to
NG
A
OK
B
INSPECT EGR VALVE ASSEMBLY
Remove the EGR valve assembly.
Check if the EGR valve is stuck open.
OK
EGR valve is tightly closed.
Result
Proceed to
OK
NG
PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)
Connect the GTS to the DLC3.
Start the engine.
Turn the GTS on.
Warm up the engine.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / All Data / O2S B1S2.
Powertrain > Engine and ECT > Active Test
Active Test Display
Control the Injection Volume for A/F Sensor
Data List Display
O2S B1S2
Change the fuel injection volume using the GTS and monitor the voltage output of the heated oxygen sensor displayed on the GTS.
Tip:The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
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.
Result
Proceed to
OK
NG
NG CHECK FOR EXHAUST GAS LEAKClick here
PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Start the engine.
Warm up the engine.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / All Data / AFS Voltage B1S1 and O2S B1S2.
Powertrain > Engine and ECT > Active Test
Active Test Display
Control the Injection Volume for A/F Sensor
Data List Display
AFS Voltage B1S1
O2S B1S2
Change the fuel injection volume using the GTS, and monitor the voltage output of the air fuel ratio sensor and heated oxygen sensor displayed on the GTS.
Tip:The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
The air fuel ratio sensor is displayed as AFS Voltage B1S1, and the heated oxygen sensor is displayed as O2S B1S2 on the GTS.
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
GTS Display (Sensor)
Voltage Variation
Proceed to
AFS Voltage B1S1 (Air fuel ratio)
Alternates between higher than and less than 3.3 V
OK
Remains at higher than 3.3 V
NG
Remains at less than 3.3 V
Tip: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 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 SENSORClick here
PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or more.
Tip:The A/C switch and all accessory switches should be off.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / All Data / MAP and Throttle Idle Position.
Powertrain > Engine and ECT > Active Test
Active Test Display
Control the EGR Step Position
Data List Display
MAP
Throttle Idle Position
Confirm that the Throttle Idle Position is ON and check the engine idling condition and MAP values in the Data List while performing the Active Test.
OK
MAP and idling condition change in response to EGR step position.
-
EGR Step Position (Active Test)
0 Steps
0 to 30 Steps
Idling condition
Steady idling
Idling changes from steady to rough idling or engine stalls
MAP
(Data List)
MAP value is 20 to 48 kPa(abs)
[150 to 360 mmHg(abs)]
(EGR valve is fully closed)
MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed
Tip: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.
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 assembly.
Result
Result
Proceed to
NG
A
OK
B
B CHECK ENGINE TO DETERMINE CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO (FUEL INJECTOR ASSEMBLY, FUEL SYSTEM, INTAKE SYSTEM, ETC.)
INSPECT EGR VALVE ASSEMBLY
Remove the EGR valve assembly.
Check if the EGR valve is stuck open.
OK
EGR valve is tightly closed.
Result
Proceed to
OK
NG
OK CHECK ENGINE TO DETERMINE CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO (FUEL INJECTOR ASSEMBLY, FUEL SYSTEM, INTAKE SYSTEM, ETC.)
CHECK FOR EXHAUST GAS LEAK
Check for exhaust gas leaks.
OK
No gas leaks.
Result
Proceed to
OK
NG
NG REPAIR OR REPLACE EXHAUST GAS LEAK POINT
INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
Inspect the heated oxygen sensor.
Result
Proceed to
OK
NG
CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)
Disconnect the heated oxygen sensor connector.
Disconnect the ECM connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection
Condition
Specified Condition
B103-1 (HT1B) - B31-22 (HT1B)
Always
Below 1 Ω
B103-3 (OX1B) - B31-103 (OX1B)
Always
Below 1 Ω
B103-4 (E2) - B31-135 (EX1B)
Always
Below 1 Ω
B103-1 (HT1B) or B31-22 (HT1B) - Body ground
Always
10 kΩ or higher
B103-3 (OX1B) or B31-103 (OX1B) - Body ground
Always
10 kΩ or higher
Result
Proceed to
OK
NG
NG REPAIR OR REPLACE HARNESS OR CONNECTOR
REPLACE HEATED OXYGEN SENSOR
Replace the heated oxygen sensor.
Result
Proceed to
NEXT
PERFORM CONFIRMATION DRIVING PATTERN
Perform Confirmation Driving Pattern.
Result
Proceed to
NEXT
CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137 OR P0138)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Powertrain > Engine and ECT > Utility
Tester Display
All Readiness
Input the DTC: P0136, P0137 or P0138.
Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again but increase the vehicle speed.
Result
Result
Proceed to
ABNORMAL
(DTC P0136, P0137 or P0138 is output)
A
NORMAL
(DTC is not output)
B
B END
PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or more.
Tip:The A/C switch and all accessory switches should be off.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / All Data / MAP and Throttle Idle Position.
Powertrain > Engine and ECT > Active Test
Active Test Display
Control the EGR Step Position
Data List Display
MAP
Throttle Idle Position
Confirm that the Throttle Idle Position is ON and check the engine idling condition and MAP values in the Data List while performing the Active Test.
OK
MAP and idling condition change in response to EGR step position.
-
EGR Step Position (Active Test)
0 Steps
0 to 30 Steps
Idling condition
Steady idling
Idling changes from steady to rough idling or engine stalls
MAP
(Data List)
MAP value is 20 to 48 kPa(abs)
[150 to 360 mmHg(abs)]
(EGR valve is fully closed)
MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed
Tip: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.
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 assembly.
Result
Result
Proceed to
NG
A
OK
B
INSPECT EGR VALVE ASSEMBLY
Remove the EGR valve assembly.
Check if the EGR valve is stuck open.
OK
EGR valve is tightly closed.
Tip:Perform "Inspection After Repair" after replacing the air fuel ratio sensor or EGR valve assembly.
Result
Proceed to
OK
NG