Inspection Procedure

HINT:

Read freeze frame data using 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.
Malfunctioning areas can be found by performing the Control the Injection Volume for A/F Sensor operation. The Control the Injection Volume for A/F Sensor operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble area are malfunctioning or not.
1. Perform the Control the Injection Volume for A/F Sensor operation.
The Control the Injection Volume for A/F Sensor operation lowers the injection volume 12.5% or increases the injection volume 25%.
1. Connect Techstream to the DLC3.
2. Turn the power switch ON (IG).
3. Put the engine in inspection mode (See SFI SYSTEM ).
4. Warm up the engine by running the engine at 2,500 rpm, depressing the accelerator pedal more than 60% for approximately 90 seconds.
5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
6. Perform the Control the Injection Volume for A/F Sensor operation with the engine in an idle condition (press the right or left button).
Result:

A/F sensor reacts in accordance with increase and decrease of injection volume:

+25% → rich output: Less than 3.0 V

-12.5% → lean output: More than 3.35 V

Heated oxygen sensor reacts 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

NOTE: The A/F sensor output has a few seconds of delay and the heated oxygen sensor output has about 20 seconds of delay at maximum.

OUTPUT VOLTAGE REFERENCE CHART

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	Fuel pressure Gas leakage from exhaust system (Air-fuel ratio extremely lean or rich)

The following Control the Injection Volume for A/F Sensor procedure enables the technician to check and graph the voltage output of both A/F sensor and heated oxygen sensor.

To display the graph, enter 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 then press the graph button on the Data List view.

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0420)

Connect Techstream to the DLC3.
Turn the power switch ON (IG).
Turn Techstream ON.
Enter the following menus: Powertrain / Engine and ECT / Trouble Code.

Read the DTCs.

Result

RESULT CHART

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

HINT:

If any other codes besides P0420 are output, perform troubleshooting for those DTCs first.

B: GO TO DTC CHART

A: Go to next step

PERFORM ACTIVE TEST BY TECHSTREAM (A/F CONTROL)

Connect Techstream to the DLC3.
Put the engine in inspection mode (See SFI SYSTEM ).
Turn the tester on.
Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
On the tester, select the following menu items: Powertrain / Engine and ECT / 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 A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2) displayed on the tester.

Result:

A/F sensor reacts in accordance with increases and decreases in fuel injection volume:

+25% = Rich output:

Less than 3.0 V

-12.5% = Lean output:

More than 3.35 V

NOTE: The A/F sensor has an output delay of a few seconds and the HO2 sensor has a maximum output delay of approximately 20 seconds.

OUTPUT VOLTAGE REFERENCE CHART

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	Fuel pressure Gas leakage from exhaust system (Air-fuel ratio extremely lean or rich)

Following the 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, select the following menu items on the tester: 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 then press the graph button on the Data List view.

Result

RESULT CHART

Result	Proceed to
Case 1	A
Case 2	B
Case 3	C
Case 4	D

B: REPLACE AIR FUEL RATIO SENSOR

C: Go to step 4

D: CHECK AND REPAIR CAUSES OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO, AND GO TO STEP 3

A: Go to next step

INSPECT FOR EXHAUST GAS LEAK
1. Check for exhaust gas leakage.
  OK:
  
  No gas leakage.
NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT

OK: REPLACE FRONT EXHAUST PIPE ASSEMBLY
INSPECT FOR EXHAUST GAS LEAK
1. Check for exhaust gas leakage.
  OK:
  
  No gas leakage.
NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT

OK: REPLACE HEATED OXYGEN SENSOR