Inspection Procedure

1. Are there any other codes (besides DTC P0420 or P0430) being output? 

   PREPARATION: 

   1. Connect the hand-held tester or the OBD II scan tool to the DLC3.
   2. Turn the ignition switch ON and push the hand-held tester or the OBD II scan tool main switch ON.
   3. When using hand-held tester, enter the following menu: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

   CHECK: 

   Read the DTC using the hand-held tester or the OBD II scan tool.

   RESULT: 

   DISPLAY DTC Output
   
   

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

   NOTE: If any other codes besides P0420 and/or P0430 are output, perform the troubleshooting for those DTCs first.
   1. B: Go to relevant DTC chart (See  DIAGNOSTIC TROUBLE CODE CHART  ) 
   2. A: Go to next step. 
2. Check gas leakage on exhaust system. 
   1. NG: Repair or replace exhaust gas leakage point. 
   2. OK: Go to next step. 
3. Check heated oxygen sensor (bank 1, 2 sensor 1) (See  CHECK HEATED OXYGEN SENSOR  in  SFI SYSTEM  ). 
   NOTE: Refer to the hint following the end of this flowchart.
   1. NG: Replace heated oxygen sensor. 
   2. OK: Go to next step. 
4. Check heated oxygen sensor (bank 1, 2 sensor 2) (See  HEATED OXYGEN SENSOR  ). 
   NOTE: Refer to the hint following the end of this flowchart.
   1. NG: Replace heated oxygen sensor. 
   2. OK: Replace front and rear three-way catalytic converter in the bank a malfunction is detected. 

1. Perform ACTIVE TEST by hand-held tester (A/F CONTROL).
   NOTE: "A/F CONTROL is the ACTIVE TEST which changes the injection volume to -12.5 % or +25 %.
   1. Connect the hand-held tester to the DLC3 on the vehicle.
   2. Turn the ignition switch ON.
   3. Warm up the engine with the engine speed at 2,500 rpm for approximately 90 seconds.
   4. Select the menu DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
   5. Perform A/F CONTROL with the engine in an idle condition (press the right or left button).

RESULT: 

Heated oxygen sensor reacts in accordance with increase and decrease of injection volume 

+25 % --> rich output: More than 0.5 V 

-12.5 % --> lean output: Less than 0.4 V 

Fig 1: Output Voltage Of Heated Oxygen Sensor Chart

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The following A/F CONTROL procedure enables the technician to check and graph the voltage output of the heated oxygen sensors (sensor 1 and 2).

For displaying the graph indication, enter ACTIVE TEST / A/F CONTROL / USER DATA then select O2S B1S1 and O2S B1S2 by pressing YES button and push ENTER button before pressing F4 button.

• If different DTCs related to different systems while terminal E2 as ground terminal are output simultaneously, terminal E2 may be open.
• Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
• A high heated oxygen sensor (sensor 1) voltage (0.5 V or more) could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
• A low heated oxygen sensor (sensor 1) voltage (0.4 V or less) could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.