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 PTC P0420) 
   1. Connect a hand-held tester to the DLC3.
   2. Turn the ignition switch to ON and turn the tester ON.
   3. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
   4. Read DTCs.
      DTC OUTPUT RESULT
      
      

      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.

   1. B: GO TO DTC CHART (See  DIAGNOSTIC TROUBLE CODE CHART  ) 
   2. 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 outputs 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: 

     FUEL INJECTION VOLUME STANDARD
     
     

     Tester Display (Sensor)	Injection Volumes	Status	Voltages
     O2S B1S1 (Front HO2 Sensor)	+25 %	Rich	More than 0.55
     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: Performing Active Test Using Hand-Held Tester (A/F Control) Table

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Rich: During A/F CONTROL, the HO2 sensor (sensors 1 and 2) output voltages are consistently more than 0.50 to 0.55 V.

   1. B: CHECK AND REPLACE OXYGEN SENSOR (SENSOR 1) 
   2. C: CHECK AND REPLACE OXYGEN NO.2 SENSOR (SENSOR 2), OR CHECK AND REPAIR EXHAUST GAS LEAKAGE 
   3. A: Go to next step 
3. CHECK FOR EXHAUST GAS LEAKAGE (SEE  REMOVAL & INSTALLATION AND DISASSEMBLY & REASSEMBLY  ) 

   OK: No gas leakage. 

   1. NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT 
   2. OK: REPLACE THREE-WAY CATALYTIC CONVERTER (EXHAUST MANIFOLD) 
   NOTE: Replace both the front and rear catalysts (front exhaust pipe).

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

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO PTC 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: 

      DTC OUTPUT RESULT
      
      

      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.

   1. B: GO TO DTC CHART (See  DIAGNOSTIC TROUBLE CODE CHART  ) 
   2. A: Go to next step 
2. CHECK FOR EXHAUST GAS LEAKAGE (SEE  REMOVAL & INSTALLATION AND DISASSEMBLY & REASSEMBLY  ) 

   OK: No gas leakage. 

   1. NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT 
   2. OK: Go to next step. 
3. INSPECT OXYGEN SENSOR(BANK1 SENSOR1) (See  DTC P0130 OXYGEN SENSOR CIRCUIT (BANK 1 SENSOR 1), DTC P2195 OXYGEN SENSOR SIGNAL STUCK LEAN (BANK1 SENSOR 1), DTC P2196 OXYGEN SENSOR SIGNAL STUCK RICH (BANK1 SENSOR 1)  ) 
   1. NG: REPLACE OXYGEN SENSOR (SENSOR 1) 
   2. OK: Go to next step. 
4. INSPECT OXYGEN NO.2 SENSOR(BANK1 SENSOR2) (See  DTC P0136 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 2), DTC P0138 HEATED OXYGEN SENSOR CIRCUIT HIGH VOLTAGE (BANK 1 SENSOR 2)  ) 
   1. NG: REPLACE OXYGEN NO.2 SENSOR (SENSOR 2) 
   2. OK: REPLACE THREE-WAY CATALYTIC CONVERTER (FRONT PIPE) 
   NOTE: Replace both the front and rear catalysts (front exhaust pipe).