Inspection Procedure

HINT:

Read freeze frame data using a hand-held tester or OBD II scan tool. Freeze frame data record 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.

Hand-held tester: 

1. Are there any other codes (besides DTC P0420) being output? 
   • YES: Go to DTC chart (See  DIAGNOSTIC TROUBLE CODE CHART   ). 
   • NO: Go to next step. 
2. Perform active test using hand-held tester (A/F CONTROL). 

   HINT:

   The A/F Control operation lowers the injection volume by 12.5% or increases the injection volume by 25%.

   PREPARATION: 

   1. Connect the hand-held tester to the DLC3.
   2. Turn the ignition switch to ON and turn the hand-held tester ON.
   3. Warm up the engine by running it at 2,500 rpm for approximately 90 seconds.
   4. On the hand-held tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.

   CHECK: 

   Perform the A/F CONTROL operation with the engine in an idling condition (press the right or left button).

   OK: 

   The heated oxygen sensors react in accordance with increases and decreases in the fuel injection volume. 

   +25% -> Rich output: More than 0.55 V (sensor 1), More than 0.5 V (sensor 2) 

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

   NOTE: The front heated oxygen sensor has an output delay of a few seconds and the rear heated oxygen sensor has a maximum output delay of approximately 20 seconds.
   Fig 1: A/F Sensor Output Voltage Chart (Sensor 1/Sensor 2)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both front and rear heated oxygen sensors.

   To display the graph, enter the following menu items: ACTIVE TEST/ A/F CONTROL / USER DATA, select O2S B1S1 and O2S B1S2 by pressing the YES button followed by the ENTER button and then the F4 button.

   RESULT: 

   ACTIVE TEST RESULT TABLE
   
   

   Results	Proceed To
   Case 1	A
   Case 2	B
   Case 3	C
   Case 4	A

   • B: Check and replace heated oxygen sensor (sensor 1) (See  DTC P0130 OXYGEN SENSOR CIRCUIT (BANK 1 SENSOR 1), DTC P0150 OXYGEN SENSOR CIRCUIT (BANK 2 SENSOR 1)   ). 
   • C: Check and replace heated oxygen sensor (sensor 2) (See  DTC P0136 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 2)   ), or check and repair exhaust gas leakage. 
   • A: Go to next step. 
3. Check exhaust system for gas leakage. 
   • NG: Repair or replace exhaust leakage point (See  EXHAUST SYSTEM  ). 
   • OK: Replace three-way catalytic converter (See  CYLINDER HEAD  and  EXHAUST SYSTEM  ). 
   NOTE: Replace both the front and rear catalysts.

OBD II scan tool (excluding the hand-held tester): 

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 to ON and turn the hand-held tester or the OBD II scan tool ON.
   3. On the hand-held tester, select the items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

   CHECK: 

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

   Result: 

   DTC OUTPUT RESULT TABLE
   
   

   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 (See  DIAGNOSTIC TROUBLE CODE CHART   ). 
   • A: Go to next step. 
2. Check gas leakage on exhaust system. 
   • NG: Repair or replace exhaust gas leakage point (See  EXHAUST SYSTEM  ). 
   • OK: Go to next step. 
3. Check oxygen sensor (bank 1 sensor 1) (See  DTC P0031 OXYGEN SENSOR HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1), DTC P0032 OXYGEN SENSOR HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 1), DTC P0037 OXYGEN SENSOR HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 2), DTC P0038 OXYGEN SENSOR HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 2), DTC P0051 OXYGEN SENSOR HEATER CONTROL CIRCUIT LOW (BANK 2 SENSOR 1), DTC P0052 OXYGEN SENSOR HEATER CONTROL CIRCUIT HIGH (BANK 2 SENSOR 1)   ). 
   • NG: Replace heated oxygen sensor. 
   • OK: Go to next step. 
4. Check heated oxygen sensor (bank 1 sensor 2) (See  DTC P0136 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 2)   ). 
   • NG: Repair or replace oxygen sensor (bank 1 sensor 2) (See  EXHAUST SYSTEM  ). 
   • OK: Replace front and rear three-way catalytic converter (See  CYLINDER HEAD  and  EXHAUST SYSTEM  ). 
   NOTE: Replace both the front and rear catalysts.