Inspection Procedure

HINT.

Malfunctioning areas can be identified by performing the A/F CONTROL*1 (Control the Injection Volume for A/F sensor*2) function provided in the Active Test The A/F CONTROL (Control the Injection Volume for A/F sensor) function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the A/F CONTROL (Control the Injection Volume for A/F sensor) operation using the intelligent tester or Techstream

*1: Intelligent tester

*2: Techstream

Connect the intelligent tester or Techstream to the DLC3.
Put the engine in inspection mode (see INSPECTION MODE PROCEDURE ).
Turn the tester ON.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
On the tester, enter the following menus.
1. Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
2. Techstream - Select. Powertrain / Engine and ECT / 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 A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.

HINT

The A/F CONTROL (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.

TYPICAL MALFUNCTION THRESHOLDS

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1 S1 or AFS B2 S1 (A/F)	+25%	Rich	Less than 3 0 V
AFS B1 S1 or AFS B2 S1 (A/F)	-12 5%	Lean	More than 3 35 V
O2S B1 S2 or O2S B2 S2 (HO2)	+25%	Rich	More than 0 55 V
O2S B1 S2 or O2S B2 S2 (HO2)	-12 5%	Lean	Less than 0 4V

NOTE: The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.

TYPICAL MALFUNCTION THRESHOLDS

Case	A/F Sensor (Sensor 1) Output Voltage	HO2 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	A/F sensor A/F sensor heater A/F sensor circuit
3	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	HO2 sensor HO2 sensor heater HO2 sensor circuit
4	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injector Fuel pressure Gas leakage from exhaust system (Air-fuel ratio extremely rich or lean)

Following the A/F CONTROL or Control the Injection Volume for A/F sensor procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.
To display the graph, enter the following menus:
1. Intelligent tester- Select: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST /A/F CONTROL /A/F CONTROL SYS / AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2; then press the YES button and the ENTER button followed by the F4 button.
2. Techstream - Select: Powertrain / Engine and ECT / 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:

When viewed from the rear of the engine assembly, Bank 1 is on the left side and Bank 2 is on the right side.
Read freeze frame data using the intelligent tester or Techstream. 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.

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

Connect the intelligent tester or Techstream to the DLC3
Turn the power switch ON (IG) and turn the tester ON.
Enter the following menus:
1. Intelligent tester - Select DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES
2. Techstream - Select" Powertrain / Engine and ECT / Trouble Codes

Read DTCs.

Result

RESULT REFERENCE

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 INTELLIGENT TESTER OR TECHSTREAM (A/F CONTROL)

Connect the intelligent tester or Techstream to the DLC3.
Put the engine in inspection mode (see INSPECTION MODE PROCEDURE ).
Turn the tester ON.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds
Enter the following menus.
1. Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL
2. Techstream - Select. Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor
Perform the A/F CONTROL (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 A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.

HINT

The A/F CONTROL (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

STANDARD CHART

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1 S1 or AFS B2 S1 (A/F)	+25%	Rich	Less than 3.0
AFS B1 S1 or AFS B2 S1 (A/F)	-12.5%	Lean	More than 3 35
O2S B1 S2 or O2S B2 S2 (HO2)	+25%	Rich	More than 0.55
O2S B1 S2 or O2S B2 S2 (HO2)	-12.5%	Lean	Less than 0.4

Result

RESULT REFERENCE

Status AFS B1 S1 or AFS B2 S1	Status O2S B1 S2 or O2S B2 S2	A/F Condition and A/F and HO2 Sensors Conditions	Misfires	Main Suspected Trouble Area	Proceed to
Lean/Rich	Lean/Rich	Normal	-	Three-Way Catalytic Converter (TWC) Gas leakage from exhaust system	A
Lean	Lean/Rich	A/F sensor malfunction	-	A/F sensor	B
Rich	Lean/Rich	A/F sensor malfunction	-	A/F sensor	B
Lean/Rich	Lean	HO2 sensor malfunction	-	HO2 sensor Gas leakage from exhaust system	C
Lean/Rich	Rich	HO2 sensor malfunction	-	HO2 sensor Gas leakage from exhaust system	C
Lean	Lean	Actual air-fuel ratio lean	May occur	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system	A
Rich	Rich	Actual air-fuel ratio rich	-	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system	A

Lean. During A/F CONTROL (Control the Injection Volume for A/F sensor), the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the HO2 sensor output voltage (O2S) is consistently less than 0.4 V

Rich. During A/F CONTROL (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 A/F CONTROL (Control the Injection Volume for A/F sensor) of the Active Test, the output voltage of the HO2 sensor alternates correctly

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

C: CHECK AND REPLACE HEATED OXYGEN SENSOR, AND CHECK AND REPAIR EXHAUST GAS LEAKAGE (See REMOVAL )

A: Go to next step

INSPECT FOR EXHAUST GAS LEAK
OK: No gas leakage.

NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT

OK: REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY (THREE-WAY CATALYTIC CONVERTER) (See REMOVAL )