Inspection Procedure

HINT:

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, 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. 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 scan tool main switch ON.
   3. Enter the following menus: DIAGNOSIS/ENHANCED OBD II/ DTC INFO /CURRENT CODES.

   CHECK: 

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

   RESULT 

   Fig 1: Display (DTC Output) Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT:

   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  INSPECTION  ). 

   HINT:

   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  INSPECTION  ). 

   HINT:

   Refer to the hint following the end of this flowchart.

   1. NG: Replace heated oxygen sensor. 
   2. OK: Go to next step. 

   Replace front and rear three-way catalytic converter. 

   HINT:

   Hand-held tester only:

   The narrowing down the trouble area is possible by performing ACTIVE TEST of the following "A/F CONTROL" (Heated oxygen sensor or another can be distinguished).

   1. Perform ACTIVE TEST by hand-held (A/F CONTROL).

   HINT:

   "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 item "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 0.5V 

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

   NOTE: However, there is a few second delay in the sensor 1 (front sensor) output. And there is about 20 seconds delay in the sensor 2 (rear sensor).