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. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420) 
   1. Connect a hand-held tester to the DLC3.
   2. Turn the ignition switch to ON and turn the tester ON.
   3. On the tester, select the following menu items: DIAGNOSIS/ENHANCED OBD II/DTC INFO/CURRENT CODES.
   4. Read DTCs.

   Result: 

   RESULT REFERENCE
   
   

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

   HINT:

   If any DTCs other than P0420 are output, troubleshoot those DTCs first.

   B  DIAGNOSTIC TROUBLE CODE CHART  ) 

   A: Go to next step. 

2. PERFORM ACTIVE TEST USING HAND HELD TESTER (A/F CONTROL) 
   1. Connect the hand-held tester to the DLC3.
   2. Turn the ignition switch to ON and turn the tester ON.
   3. Start the engine.
   4. Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
   5. On the tester, select the following menu items: DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/A/F CONTROL.
   6. Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
   7. Monitor the voltage output of the HO2 sensors (O2S B1S1 and OS2 B1S2) displayed on the tester.

   HINT:

   • The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection volume by 25 %.
   • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

   Standard: 

   DISPLAY STATUS
   
   

   Tester Display (Sensor)	Injection Volumes	Status	Voltages
   O2S B1S1 (Front HO2 Sensor)	+25 %	Rich	More than 0.5
   O2S B1S1 (Front HO2 Sensor)	-12.5%	Lean	Less than 0.4
   O2S B1S2 (Rear HO2 Sensor)	+25 %	Rich	More than 0.5
   O2S B1S2 (Rear HO2 Sensor)	-12.5%	Lean	Less than 0.4

   Result: 

   Fig 1: Result Reference Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Lean: During A/F CONTROL, the HO2 sensor (sensors 1 and 2) output voltages are consistently less than 0.4V.

   Rich: During A/F CONTROL, the HO2 sensor (sensors 1 and 2) output voltages are consistently more than 0.5V.

   B: CHECK AND REPLACE HEATED OXYGEN SENSOR (SENSOR 1) (See  DTC P0130 OXYGEN SENSOR CIRCUIT MALFUNCTION (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)  ) 

   C: CHECK AND REPLACE HEATED OXYGEN SENSOR (SENSOR 2) (See  DTC P0136 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 2), DTC P0138 OXYGEN SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 2)  ), AND CHECK AND REPAIR EXHAUST GAS LEAKAGE 

   A: Go to next step. 

3. CHECK FOR EXHAUST GAS LEAKAGE 

   OK: No gas leakage. 

   NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT 

   OK: REPLACE THREE-WAY CATALYTIC CONVERTER 

   NOTE: Replace both the front catalyst (exhaust manifold) and rear catalyst (exhaust center pipe).

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

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420) 
   1. Connect an OBD II scan tool to the DLC3.
   2. Turn the ignition switch to ON and turn the scan tool ON.
   3. Read DTCs using the scan tool.

   Result: 

   RESULT REFERENCE
   
   

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

   HINT:

   If any DTCs other than P0420 are output, troubleshoot those DTCs first.

   B:  DIAGNOSTIC TROUBLE CODE CHART  ) 

   A: Go to next step. 

2. CHECK FOR EXHAUST GAS LEAKAGE 

   OK: No gas leakage. 

   NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT 

   OK: Go to next step. 

3. INSPECT HEATED OXYGEN SENSOR (SENSOR 1) (See  DTC P0130 OXYGEN SENSOR CIRCUIT MALFUNCTION (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: REPLACE HEATED OXYGEN SENSOR 

   OK: Go to next step. 

4. INSPECT HEATED OXYGEN SENSOR (SENSOR 2) (See  DTC P0136 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 2), DTC P0138 OXYGEN SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 2)  ) 

   NG: REPLACE HEATED OXYGEN SENSOR 

   OK: REPLACE THREE-WAY CATALYTIC CONVERTER 

   NOTE: Replace both the front catalyst (exhaust manifold) and rear catalyst (exhaust center pipe).