2Tr-Fe Engine Control. Dtc P0136 Oxygen Sensor Circuit (Bank 1 Sensor 2)

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 Three-way Catalytic Converter (TWC) is used. For the most efficient use of the Three-way Catalytic Converter (TWC), the air-fuel ratio must be precisely controlled so that it is always close to 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 (TWC), and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with a 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-Three-way Catalytic Converter (TWC) air-fuel ratio is lean (low voltage, i.e. below 0.45 V).
Conversely, when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, the oxygen concentration in the exhaust gas becomes lean. The heated oxygen sensor informs the ECM that the post-Three-way Catalytic Converter (TWC) air-fuel ratio is rich (high voltage, i.e. higher 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 (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 primary air-fuel ratio control.

Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.2Tr-Fe Engine Control.Sfi System.
Dtc
P0136 Oxygen Sensor Circuit (Bank 1 Sensor 2)

DTC No.	DTC Detection Condition	Trouble Area
P0136	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): (a) Heated oxygen sensor voltage does not increase to higher than 0.71 V. (b) Heated oxygen sensor voltage does not decrease to below 0.21 V.	Open or short in heated oxygen sensor circuit Heated oxygen sensor Heated oxygen sensor heater Air fuel ratio sensor Gas leak from exhaust system
P0137	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): (a) Heated oxygen sensor voltage output is below 0.21 V. (b) Target air-fuel ratio is rich.	Open in heated oxygen sensor circuit Heated oxygen sensor Heated oxygen sensor heater Air fuel ratio sensor Gas leak from exhaust system
P0138	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): (a) Heated oxygen sensor voltage output is higher than 0.71 V. (b) Target air-fuel ratio is lean.	Short in heated oxygen sensor circuit Heated oxygen sensor Air fuel ratio sensor ECM

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 ratio. 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 below 0.21 V and does not increase to higher than 0.71 V 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, or the voltage output of the sensor decreases significantly, the Oxygen Storage Capacity (OSC) is indicated as having 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 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 0.71 V or more (rich) during active air-fuel ratio control, the ECM determines that the sensor voltage output is abnormally high and stores DTC P0138.
*: The Three-way Catalytic Converter (TWC) has the capability to store oxygen. The Oxygen Storage Capacity (OSC) and the emissions purification capacity of the Three-way Catalytic Converter (TWC) are mutually related. The ECM determines whether the catalyst has deteriorated based on the calculated Oxygen Storage Capacity (OSC) value (LandCruiser RM000000TMD0EYX.html).

MONITOR STRATEGY

Required Sensors/Components (Main)	Heated oxygen sensor
Required Sensors/Components (Related)	Crankshaft position sensor, engine coolant temperature sensor, mass air flow meter sub-assembly, throttle position sensor and air fuel ratio sensor
Frequency of Operation	Once per driving cycle: Active air-fuel ratio control detection Continuous: Other

TYPICAL ENABLING CONDITIONS

Heated Oxygen Sensor Output Voltage (Abnormal Voltage Output, High Voltage and Low Voltage)
Active air-fuel ratio control	Executing
Active air-fuel ratio control begins when all of following conditions 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 to 80%

TYPICAL MALFUNCTION THRESHOLDS

Heated Oxygen Sensor Output Voltage (Abnormal Voltage Output)
Either of following conditions met:	1 or 2
1. Both of following conditions met	(a) and (b)
(a) Commanded air-fuel ratio	14.3 or less
(b) Rear heated oxygen sensor voltage	0.21 to 0.71 V
2. Both of following conditions met	(c) and (d)
(c) Commanded air-fuel ratio	14.8 or more
(d) Rear heated oxygen sensor voltage	0.21 to 0.71 V

Heated Oxygen Sensor Output Voltage (Low)
Both of following conditions met	(a) and (b)
(a) Commanded air-fuel ratio	14.3 or less
(b) Rear heated oxygen sensor voltage	Below 0.21 V

Heated Oxygen Sensor Output Voltage (High)
Both of following conditions met	(a) and (b)
(a) Commanded air-fuel ratio	14.8 or more
(b) Rear heated oxygen sensor voltage	Higher than 0.71 V

CONFIRMATION DRIVING PATTERN

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 operation).
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 transmission in 5th gear or higher, drive the vehicle at 90 to 120 km/h (56 to 75 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.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. 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

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, shift the transmission to 3rd gear, and then perform steps [C] and [D] again.

WIRING DIAGRAM

Refer to DTC P2195 (LandCruiser RM000000WC40YKX_07.html).

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 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 and 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.
Perform the Active Test operation with the engine idling.
Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the GTS.

HINT:

Change the fuel injection volume within the range of -12.5% to +12.5%.
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.

GTS Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1S1 (A/F)	+12.5%	Rich	Below 3.1 V
AFS Voltage B1S1 (A/F)	-12.5%	Lean	Higher than 3.4 V
O2S B1S2 (HO2)	+12.5%	Rich	Higher than 0.55 V
O2S B1S2 (HO2)	-12.5%	Lean	Below 0.4 V

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.

Case	Air Fuel Ratio Sensor (Sensor 1) Output Voltage	Heated Oxygen Sensor (Sensor 2) Output Voltage	Main Suspected Trouble Area
1			-
2			Air fuel ratio sensor Air fuel ratio sensor heater Air fuel ratio sensor circuit
3			Heated oxygen sensor Heated oxygen sensor heater Heated oxygen sensor circuit
4			Fuel injector assembly Fuel pressure Gas leak from exhaust system (air-fuel ratio extremely rich or lean)

HINT:

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 / Data List / AFS Voltage B1S1 and O2S B1S2.
Read freeze frame data using the GTS. 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.
If the OX1B wire from the ECM connector is short-circuited to the +B wire, DTC P0136 will be stored.
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.

1.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 DTCs.

Result
Result
Proceed to
P0138 is output
A
P0137 is output
B
P0136 is output
C
P0136, P0137 or P0138 and other DTCs are output
D

Result
Result	Proceed to
P0138 is output	A
P0137 is output	B
P0136 is output	C
P0136, P0137 or P0138 and other DTCs are output	D

Go to step 9

Go to step 7

GO TO DTC CHART (LandCruiser RM000000VNN00FX.html)

A

2.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.

Enter the following menus: Powertrain / Engine and ECT / Data List / 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
Below 1.0 V
B

Go to step 5

A

3.INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)

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
Text in Illustration
*a
Component without harness connected
(to Heated Oxygen Sensor)

Text in Illustration
*a	Component without harness connected (to Heated Oxygen Sensor)

REPLACE HEATED OXYGEN SENSOR (LandCruiser RM00000175F00UX.html)

OK

4.CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)

Turn the ignition switch off and wait for 5 minutes.

Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection
Condition
Specified Condition
C154-7 (HT1B) - C154-27 (OX1B)
Always
10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE ECM (LandCruiser RM000000VW203EX.html)

5.PERFORM ACTIVE TEST USING GTS (INJECTION VOLUME)

Connect the GTS to the DLC3.

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.

Change the fuel injection volume using the GTS and monitor the voltage output of the air fuel ratio and heated oxygen sensors displayed on the GTS.

HINT:

Change the fuel injection volume within the range of -12.5% to +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.
If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

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
GTS Display (Sensor)
Voltage Variation
Proceed to
AFS Voltage B1S1
Alternates between higher than and below 3.3 V
OK
Remains higher than 3.3 V
NG
Remains below 3.3 V
NG
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 remains either below or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.

Result
GTS Display (Sensor)	Voltage Variation	Proceed to
AFS Voltage B1S1	Alternates between higher than and below 3.3 V	OK
Remains higher than 3.3 V	NG
Remains below 3.3 V	NG

Go to step 15

OK

6.INSPECT AIR FUEL RATIO SENSOR

HINT:

This air fuel ratio sensor test is to check the air fuel ratio sensor current during the fuel-cut. When the sensor is normal, the sensor current will be below 2.2 mA in this test.

Clear DTCs (LandCruiser RM000000VNG00DX.html).

Drive the vehicle according to the driving pattern listed below.
1. Warm up the engine.
2. Drive the vehicle at 60 km/h (37 mph) or more for 10 minutes or more.
3. Stop the vehicle.
4. Accelerate the vehicle to 60 km/h (37 mph) or more and decelerate for 5 seconds or more. Perform this 3 times.

Enter the following menus: Powertrain / Engine and ECT / Data List / AFS Current B1S1.

Read the value of the air fuel ratio sensor current while the fuel-cut operation is being performed.
Standard current:
Below 2.2 mA
HINT:
1. To measure the air fuel ratio sensor current precisely, perform the fuel-cut operation as long as possible.
2. If it is difficult to measure the air fuel ratio sensor current, use the snapshot function of the GTS.

Go to step 12

Go to step 15

7.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 / Data List / O2S B1S2.

Change the fuel injection volume using the GTS and monitor the voltage output of the heated oxygen sensors displayed on the GTS.
HINT:
1. Change the fuel injection volume within the range of -12.5% to +12.5%.
2. 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.
Standard voltage:
Fluctuates between 0.4 V or less and 0.5 V or higher.

Go to step 9

OK

8.PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)

Connect the GTS to the DLC3.

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.

Change the fuel injection volume using the GTS and monitor the voltage output of the air fuel ratio and heated oxygen sensors displayed on the GTS.

HINT:

Change the fuel injection volume within the range of -12.5% to +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.
If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

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
GTS Display (Sensor)
Voltage Variation
Proceed to
AFS Voltage B1S1
Alternates between higher than and below 3.3 V
OK
Remains higher than 3.3 V
NG
Remains below 3.3 V
NG
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 remains either below or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.

Go to step 15

CHECK EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO AND REPAIR CAUSE (FUEL INJECTOR ASSEMBLY, FUEL PRESSURE, GAS LEAK FROM SYSTEM)

9.CHECK FOR EXHAUST GAS LEAK

Check for exhaust gas leakage.
OK:
No gas leakage.
HINT:
Perform "Inspection After Repair" after repairing or replacing the exhaust system (LandCruiser RM000004NJC03XX.html).

REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT

OK

10.INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

Inspect the heated oxygen sensor (LandCruiser RM00000175E00UX.html).

REPLACE HEATED OXYGEN SENSOR (LandCruiser RM00000175F00UX.html)

OK

11.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
C27-1 (HT1B) - C154-7 (HT1B)	Always	Below 1 Ω
C27-3 (OX1B) - C154-27 (OX1B)	Always	Below 1 Ω
C27-4 (E2) - C154-35 (EX1B)	Always	Below 1 Ω
C27-1 (HT1B) or C154-7 (HT1B) - Body ground	Always	10 kΩ or higher
C27-3 (OX1B) or C154-27 (OX1B) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

12.REPLACE HEATED OXYGEN SENSOR

Replace the heated oxygen sensor (LandCruiser RM00000175F00UX.html).

NEXT

13.PERFORM CONFIRMATION DRIVING PATTERN

Perform Confirmation Driving Pattern (P0136, P0137 and P0138).

NEXT

14.CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137 OR P0138 IS OUTPUT AGAIN)

Connect the GTS to the DLC3.

Turn the GTS on.

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Input DTCs: P0136, P0137 and 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
Display (DTC Output)
Proceed to
ABNORMAL
(P0136, P0137 or P0138 output)
A
NORMAL
(No DTC output)
B
HINT:
Perform "Inspection After Repair" after replacing the air fuel ratio sensor (LandCruiser RM000004NJC03XX.html).

END

REPLACE AIR FUEL RATIO SENSOR (LandCruiser RM00000175900NX.html)

15.REPLACE AIR FUEL RATIO SENSOR

Replace the air fuel ratio sensor (LandCruiser RM00000175900NX.html).
HINT:
Perform "Inspection After Repair" after replacing the air fuel ratio sensor (LandCruiser RM000004NJC03XX.html).

NEXT

16.PERFORM CONFIRMATION DRIVING PATTERN

Perform Confirmation Driving Pattern (P0136, P0137 and P0138).

NEXT

17.CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137 OR P0138 IS OUTPUT AGAIN)

Connect the GTS to the DLC3.

Turn the GTS on.

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Input DTCs: 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
Display (DTC Output)
Proceed to
ABNORMAL
(P0136, P0137 or P0138 output)
A
NORMAL
(No DTC output)
B

END

REPLACE HEATED OXYGEN SENSOR (LandCruiser RM00000175F00UX.html)

Heated Oxygen Sensor Output Voltage	Proceed to
1.0 V or higher	A
Below 1.0 V	B

Display (DTC Output)	Proceed to
ABNORMAL (P0136, P0137 or P0138 output)	A
NORMAL (No DTC output)	B