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Home >> Toyota >> 2006 >> Corolla CE, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 1 (Engine Control System (SFI) (2ZZ-GE) - Diagnostics) >> DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1) >> Inspection Procedure >> Hand-held tester:

Hand-held tester:

WARNING: This page is about a different variant/trim than selected.
  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: 

      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  DIAGNOSTIC TROUBLE CODE CHART  
    2. A: GO TO NEXT STEP 
  2. PERFORM ACTIVE TEST (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: 

      ACTIVE TEST

      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: Active Test Result
      G02599349Courtesy 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 0.5 V.

      Lean / Rich: During A/F CONTROL, the HO2 sensor (sensors 1 and 2) output voltages alternates between more than 0.5 V and less than 0.4 V

    1. B: CHECK AND REPLACE HEATED OXYGEN SENSOR 
    2. C: CHECK AND REPLACE HEATED OXYGEN SENSOR, AND 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: GO TO NEXT STEP 

      REPLACE THREE-WAY CATALYTIC CONVERTER (FRONT PIPE) 

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