Inspection Procedure

HINT:

Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame records the engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine 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 the malfunction occurred.

1. Are there any other codes (besides DTC P0420) 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. Select the item "DIAGNOSIS/ENHANCED OBD II/DTC INFO/CURRENT CODES".

   CHECK: 

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

   Result: 

   DISPLAY (DTC OUTPUT) SPECIFICATION
   
   

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

   HINT:

   If any other codes besides "P0420" 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 for gas leakage in exhaust system. 

   NG: Repair or replace exhaust gas leakage point. 

   OK: Go to next step. 

3. Check heated oxygen sensor (bank 1 sensor 1) (See  DTC P0130 OXYGEN SENSOR CIRCUIT (BANK 1 SENSOR 1), DTC P2195: OXYGEN SENSOR SIGNAL STUCK LEAN (BANK 1 SENSOR 1), DTC P2196: OXYGEN SENSOR SIGNAL STUCK RICH (BANK 1 SENSOR 1)  ). 

   NG: Repair or replace oxygen sensor (bank 1 sensor 1). 

   OK: Go to next step. 

4. Check heated oxygen sensor (bank 1 sensor 2) (See  DTC P0130 OXYGEN SENSOR CIRCUIT (BANK 1 SENSOR 1), DTC P2195: OXYGEN SENSOR SIGNAL STUCK LEAN (BANK 1 SENSOR 1), DTC P2196: OXYGEN SENSOR SIGNAL STUCK RICH (BANK 1 SENSOR 1)  ). 

   NG: Repair or replace oxygen sensor (bank 1 sensor 2). 

   OK: Replace three-way catalytic converter. 

   HINT:

   Hand-held tester only:

   • The following procedure enables the technician to identify a trouble area if malfunction in both front and rear heated oxygen sensors other than the catalyst converter, or the malfunction that indicates the actual air-fuel ratio extremely RICH or LEAN.
   • Narrowing down the trouble area is possible by performing "A/F CONTROL" ACTIVE TEST (heated oxygen sensor or other trouble areas can be distinguished).
   1. Perform ACTIVE TEST using the hand-held tester (A/F CONTROL).

   HINT:

   "A/F CONTROL" is ACTIVE TEST which changes the injection volume -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 by running the engine at 2,500 RPM for approximately 3 minutes.
   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 0.55 V 

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

   NOTE: There is a delay of few seconds in the sensor 1 (front sensor) output, and there is about 20 seconds delay at maximum in the sensor 2 (rear sensor).
   Fig 1: Output Voltage Of Heated Oxygen Sensor Specification Chart (Rear And Front)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   The following A/F CONTROL procedure enables the technician to check and graph the voltage outputs of both the heated oxygen sensors.

   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.