3Gr-Fe Engine Control System. Dtc P0136 Oxygen Sensor Circuit Malfunction (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 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 (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 has is rich. The HO2 sensor informs the ECM that the post-TWC air-furl 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.

Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-Fe Engine Control System.Sfi System.
Dtc
P0136 Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)

DTC No.	DTC Detection Condition	Trouble Area
P0136 P0156	During active control, heated oxygen sensor output voltage 0.2 to 0.6 V	Open or short in heated oxygen sensor (bank 1, 2 sensor 2) circuit Heated oxygen sensor (bank 1, 2 sensor 2) Heated oxygen sensor heater (bank 1, 2 sensor 2) Integration relay
P0136 P0156	(a) and (b) are met for more than 90 seconds: (a) Estimated rear oxygen sensor temperature is less than 800°C (1,472°F) (b) Rear oxygen sensor impedance is less than 5 Ω
P0137 P0157	During active control, heated oxygen sensor output voltage less than 0.2 V
P0137 P0157	(a) and (b) are met for more than 90 seconds: (a) Estimated rear oxygen sensor temperature is less than 450°C (842°F) (b) Rear oxygen sensor impedance is more than 15 Ω
P0138 P0158	During active control, heated oxygen sensor output voltage more than 0.6 V
P0138 P0158	Rear oxygen sensor output voltage is 1.2 V or higher for more than 30 seconds

HINT:

Bank 1 refers to the bank that includes cylinder No. 1.
Bank 2 refers to the bank that does not include cylinder No. 1.
Sensor 2 refers to the sensor farthest away from the engine assembly.

WIRING DIAGRAM

CONFIRMATION DRIVING PATTERN

HINT:

Performing this confirmation pattern will activate the DTC detection (P0136) of the ECM. This is very useful for verifying the completion of the repair.

(a) Clear the DTCs (Click here).

(b) Switch the ECM From normal mode to check mode using the tester (Click here).

(d) Deactivate the inspection mode and drive the vehicle at 70 to 120 km/h (44 to 70 mph) for 5 to 10 minutes.

(e) Read DTCs.

NOTICE:

If the conditions in this test are not strictly followed, no malfunction will be detected.
Do not drive the vehicle without deactivating inspection mode. Otherwise damaging the transaxle may result.

INSPECTION PROCEDURE

(a) Connect the intelligent tester to the DLC3.

HINT:

The malfunctioning areas can be found using the Active Test "Control the Injection Volume for A/F Sensor" operation. The Active Test can determine if the HO2S or other potential trouble areas are malfunctioning or not..

(b) Turn the engine switch on (IG).
(c) Warm up the engine with the engine speed at 2,500 rpm for approximately 90 seconds.
(d) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor.
(d) Perform the Active Test at the engine idling.
Standard voltage:
Heated oxygen sensor reaacts in accordance with increase and decrease of injection volume:
+25 % → rich output: More than 0.55 V
-12.5 % → lean output: Less than 0.4 V

NOTICE:

There is a few seconds delay in the A/F sensor output and there is about 20 seconds delay in the heated oxygen sensor output.

Case	A/F Sensor (Sensor 1) Output Voltage	HO2 Sensor (Sensor 2) Output Voltage	Main Suspected Trouble Area
1	Injection Volume +25 % -12.5 %	Injection Volume +25 % -12.5 %	-
1	Output Voltage More than 3.35 V Less than 3.0 V	Output Voltage More than 0.55 V Less than 0.4 V	-
2	Injection Volume +25 % -12.5 %	Injection Volume +25 % -12.5 %	A/F sensor A/F sensor heater A/F sensor circuit
2	Output Voltage Almost no reaction	Output Voltage More than 0.55 V Less than 0.4 V	A/F sensor A/F sensor heater A/F sensor circuit
3	Injection Volume +25 % -12.5 %	Injection Volume +25 % -12.5 %	HO2 sensor HO2 sensor heater HO2 sensor circuit
3	Output Voltage More than 3.35 V Less than 3.0 V	Output Voltage Almost no reaction	HO2 sensor HO2 sensor heater HO2 sensor circuit
4	Injection volume +25 % -12.5 %	Injection Volume +25 % -12.5 %	Injector Fuel pressure Gas leakage from exhaust system (Air-fuel ratio extremely lean or rich)
4	Output Voltage Almost no reaction	Output Voltage Almost no reaction

HINT:

Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, 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.

1.CHECK OTHER DTC OUTPUT (BESIDES DTC P0136, P0137, P0138, P0156, P0157 AND/OR P0158)

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG) and turn the tester ON.

Enter the following menus: Powertrain / Engine / DTC.

Read DTCs.

Result:
Display (DTC Output)
Proceed to
Only P0136, P0137, P0138, P0156, P0157 and/or P0158 are output
A
P0136, P0137, P0138, P0156, P0157 and/or P0158 and other DTCs are output
B
HINT:
If any other codes besides P0136, P0137, P0138, P0156, P0157 and/or P0158 are output, perform the troubleshooting for those DTCs first.

Result:
Display (DTC Output)	Proceed to
Only P0136, P0137, P0138, P0156, P0157 and/or P0158 are output	A
P0136, P0137, P0138, P0156, P0157 and/or P0158 and other DTCs are output	B

GO TO DTC CHART

A

2.READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)

After warming up the engine, race the engine at 2,500 rpm for 3 minutes.

Read the output voltage of the heated oxygen sensor when the engine is suddenly raced.
HINT:
Perform a quick racing to 4,000 rpm 3 times by using the accelerator pedal.
Standard voltage:
Alternate 0.4 V or less and 0.5 V or more.

Go to step 7

NG

3.INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

Disconnect the L34 or L57 HO2 sensor connector.

Measure the resistance.
Standard resistance (Bank 1 Sensor 2):
Tester Connection
Specified Condition
HT (1) - +B (2)
11 to 16 Ω at 20°C (68°F)
HT (1) - E (4)
10 kΩ or higher
Standard resistance (Bank 2 Sensor 2):
Tester Connection
Specified Condition
HT2B (L57-1) - +B (L57-2)
11 to 16 Ω at 20°C (68°F)
HT2B (L57-1) - E2 (L57-4)
10 kΩ or higher

REPLACE OXYGEN SENSOR

OK

4.INSPECT FUSE (EFI NO. 2 FUSE)

Remove the EFI NO. 2 fuse from the engine room No. 2 relay block.

Measure the resistance of the fuse.
Standard resistance:
Below 1 Ω

REPLACE FUSE

OK

5.INSPECT INTEGRATION RELAY (EFI MAIN RELAY)

Remove the integration relay from the engine room No. 2 junction block.

Inspect the EFI MAIN relay.
Standard resistance:
Tester Connection
Specified Condition
2C-1 - 2A-8
10 kΩ or higher
2C-1 - 2A-8
Below 1 Ω
(Apply battery voltage between terminals 2C-1 and 2A-8

REPLACE INTEGRATION RELAY

OK

6.CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)

Disconnect the L34 and L57 heated oxygen sensor connectors.

Disconnect the A7 ECM connector.

Measure the resistance of the connectors.

Standard resistance (Check for open):

Tester Connection	Specified Condition
OX1B (L34-3) - OX1B (A7-28)	Below 1 Ω
HT (L34-1) - HT1B (A7-2)	Below 1 Ω
E (L34-4) - O1B- (A7-29)	Below 1 Ω
OX2B (L57-3) - OX2B (A7-17)	Below 1 Ω
HT2B (L57-1) - HT2B (A7-1)	Below 1 Ω
E2 (L57-4) - O2B- (A7-18)	Below 1 Ω

Standard resistance (Check for short):

Tester Connection	Specified Condition
OX1B (L34-3) or OX1B (A7-28) - Body ground	10 kΩ or higher
HT (L34-1) or HT1B (A7-2) - Body ground	10 kΩ or higher
E (L34-4) or O1B- (A7-29) - Body ground	10 kΩ or higher
OX2B (L57-3) or OX2B (A7-17) - Body ground	10 kΩ or higher
HT2B (L57-1) or HT2B (A7-1) - Body ground	10 kΩ or higher
E2 (L57-4) or O2B- (A7-18) - Body ground	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE OXYGEN SENSOR

7.PERFORM CONFIRMATION DRIVING PATTERN

HINT:

Clear all DTCs prior to performing the confirmation driving pattern.

NEXT

8.READ OUTPUT DTC (DTC P0136 AND/OR P0156 ARE OUTPUT AGAIN)

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG) and turn the tester ON.

Enter the following menus: Powertrain / Engine / DTC.

Read DTCs.

Result:
Display (DTC Output)
Proceed to
P0136 and/or P0156 are not output again
A
P0136 and/or P0156 are output again
B

Result:
Display (DTC Output)	Proceed to
P0136 and/or P0156 are not output again	A
P0136 and/or P0156 are output again	B

REPLACE OXYGEN SENSOR

CHECK FOR INTERMITTENT PROBLEMS

Tester Connection	Specified Condition
HT (1) - +B (2)	11 to 16 Ω at 20°C (68°F)
HT (1) - E (4)	10 kΩ or higher

Tester Connection	Specified Condition
HT2B (L57-1) - +B (L57-2)	11 to 16 Ω at 20°C (68°F)
HT2B (L57-1) - E2 (L57-4)	10 kΩ or higher

Tester Connection	Specified Condition
2C-1 - 2A-8	10 kΩ or higher
2C-1 - 2A-8	Below 1 Ω (Apply battery voltage between terminals 2C-1 and 2A-8