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 Techstream

Connect the Techstream to the DLC3.
Start the engine and turn the Techstream ON
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Enter the following menus Powertrain / Engine / Active Test / Control the Injection Volume for A/F sensor
Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume)

Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the Techstream

HINT.

The Control the Injection Volume for A/F sensor operation lowers the fuel injection volume by 12 5% or increases the injection volume by 25%

Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

INSPECTION PROCEDURE CHART

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1 S1 or AFS B2 S1 (Air fuel ratio)	+25%	Rich	Less than 3 0V
AFS B1 S1 or AFS B2 S1 (Air fuel ratio)	-12 5%	Lean	More than 3 35 V
O2S B1 S2 or O2S B2 S2 (Heated oxygen)	+25%	Rich	More than 0 55 V
O2S B1 S2 or O2S B2 S2 (Heated oxygen)	-12 5%	Lean	Less than 0 4V

NOTE: 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.

AIR FUEL RATIO SENSOR REFERENCE CHART

Case	Air fuel ratio Sensor (Sensor 1) Output Voltage	Heated oxygen Sensor (Sensor 2) Output Voltage	Main Suspected Trouble Area
1	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	-
2	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Air fuel ratio sensor Air fuel ratio sensor heater Air fuel ratio sensor circuit
3	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Heated oxygen sensor Heated oxygen sensor heater Heated oxygen sensor circuit
4	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injector Fuel pressure Gas leaks from exhaust system (Air fuel ratio extremely rich or lean)

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 / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2

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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DT P0420 AND/OR P0430)

Connect the Techstream to the DLC3
Turn the engine switch on (IG) and turn the Techstream ON
Enter the following menus Powertrain / Engine / Trouble Codes

Read the DTCs

Result

RESULT CHART

Display (DTC Output)	Proceed to
P0420 and/or P0430	A
P0420 and/or P0430 and other DTCs	B

HINT

If any DTCs other than P0420 or P0430 are output, troubleshoot those DTCs first.

B: GO TO DTC CHART (See DIAGNOSTIC TROUBLE CODE CHART )

A: Go to Next Step

PERFORM ACTIVE TEST USING TECHSTREAM (AIR FUEL RATIO CONTROL)

Connect the Techstream to the DLC3
Start the engine and turn the Techstream ON
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Enter the following menus Powertrain / Engine / Active Test / Control the Injection Volume for A/F sensor
Perform the Control the Injection Volume for A/F sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume)

Monitor the voltage outputs of the air fuel ratio and heated oxygen sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the Techstream

HINT.

The Control the Injection Volume for A/F sensor operation lowers the fuel injection volume by 12 5% or increases the injection volume by 25%

Each sensor reacts in accordance with increases and decreases in the fuel injection volume

Standard

INSPECTION PROCEDURE CHART

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1 S1 or AFS B2 S1 (Air fuel ratio)	+25%	Rich	Less than 3.0
AFS B1 S1 or AFS B2 S1 (Air fuel ratio)	-12.5%	Lean	More than 3 35
O2S B1 S2 or O2S B2 S2 (Heated oxygen)	+25%	Rich	More than 0.55
O2S B1 S2 or O2S B2 S2 (Heated oxygen)	-12.5%	Lean	Less than 0.4

Result

RESULT CHART

Status AFS B1 S1 or AFS B2 S1	Status O2S B1 S2 or O2S B2 S2	Air Fuel Ratio Condition and Air Fuel Ratio and Heated Oxygen Sensors Conditions	Misfire	Main Suspected Trouble Area	Proceed to
Lean/Rich	Lean/Rich	Normal	-	Three-Way Catalytic Converter (TWC) Gas leaks from exhaust system	A
Lean	Lean/Rich	Air fuel ratio sensor malfunction	-	Air fuel ratio sensor	B
Rich	Lean/Rich	Air fuel ratio sensor malfunction	-	Air fuel ratio sensor	B
Lean/Rich	Lean	Heated oxygen sensor malfunction	-	Heated oxygen sensor Gas leaks from exhaust system	C
Lean/Rich	Rich	Heated oxygen sensor malfunction	-	Heated oxygen sensor Gas leaks from exhaust system	C
Lean	Lean	Actual air fuel ratio lean	May occur	Extremely rich or lean actual air fuel ratio Gas leaks from exhaust system	D
Rich	Rich	Actual air fuel ratio rich	-	Extremely rich or lean actual air fuel ratio Gas leaks from exhaust system	D
Lean During Control the Injection Volume for A/F sensor, the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the heated oxygen sensor output voltage (O2S) is consistently less than 0.4 V Rich During Control the Injection Volume for A/F sensor, the AFS is consistently less than 3 0 V, and the O2S is consistently more than 0 55 V Lean/Rich During Control the Injection Volume for A/F sensor of the Active Test, the output voltage of the heated oxygen sensor alternates correctly

B: CHECK AND REPLACE AIR FUEL RATIO SENSOR (See REMOVAL )

C: Go to step 7

D: Go to step 8

A: Go to Next Step

INSPECT EXHAUST GAS LEAK
OK: No gas leaks.

NG: REPAIR OR REPLACE EXHAUST GAS LEAK POINT

OK: Go to Next Step

CHECK DTC OUTPUT (DTC P0420 AND/OR P0430)

Connect the Techstream to the DLC3.
Turn the engine switch on (IG) and turn the Techstream ON
Enter the following menus. Powertrain / Engine / Trouble Codes

Read the DTCs

Result

RESULT CHART

Display (DTC Output)	Proceed to
P0420	A
P0430	B
P0420 and P0430	A and B

B: Go to step 6

A: Go to Next Step

REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY RH
1. Replace exhaust manifold sub-assembly RH (See REMOVAL ).
NEXT: REPLACE FRONT EXHAUST PIPE ASSEMBLY (See REMOVAL )
REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH
1. Replace exhaust manifold sub-assembly LH (See REMOVAL ).
NEXT: REPLACE FRONT EXHAUST PIPE ASSEMBLY (See REMOVAL )
INSPECT FOR EXHAUST GAS LEAK
OK: No gas leaks.

NG: REPAIR OR REPLACE EXHAUST GAS LEAK POINT

OK: REPLACE HEATED OXYGEN SENSOR (See REMOVAL )
INSPECT FOR EXHAUST GAS LEAK
OK: No gas leaks.

NG: REPAIR OR REPLACE EXHAUST GAS LEAK POINT

OK: CHECK ENGINE TO DETERMINE CAUSE OF EXTREMELY RICH OR LEARN ACTUAL AIR FUEL RATIO (See DTC P0171 SYSTEM TOO LEAN (BANK 1); DTC P0172 SYSTEM TOO RICH (BANK 1); DTC P0174 SYSTEM TOO LEAN (BANK 2); DTC P0175 SYSTEM TOO RICH (BANK 2); DTC P1170 PORT INJECTOR FUEL PERFORMANCE; DTC P117B DIRECT INJECTOR FUEL PERFORMANCE )