Inspection Procedure

HINT:

Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions 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.

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420) 
   1. Connect the intelligent tester to the DLC3.
   2. Turn the ignition switch ON and turn the tester ON.
   3. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
   4. Read DTCs (see DTC CHECK / CLEAR  ).

      Result 

      RESULT CHART
      
      

      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 : GO TO  DTC CHART  

   A : Go to next step 

2. PERFORM ACTIVE TEST BY INTELLIGENT TESTER (A/F CONTROL) 
   1. Connect the intelligent tester to the DLC3.
   2. Turn the ignition switch 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. Enter the following menus: 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 O2S 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: 

      DIAGNOSIS PROCEDURE
      
      

      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

      DIAGNOSIS PROCEDURE
      
      

      Status O2S B1S1	Status O2S B1S2	A/F Condition and HO2 Sensors (sensors 1 and 2) Condition	Misfires	Main Suspected Trouble Areas	Proceed to
      Lean / Rich	Lean / Rich	Normal	-	TWC Gas leakage from exhaust system	A
      Lean	Lean / Rich	HO2 sensor (sensor 1) malfunction	-	HO2 sensor (sensor 1)	B
      Rich	Lean / Rich	HO2 sensor (sensor 1) malfunction	-	HO2 sensor (sensor 1)	B
      Lean / Rich	Lean	HO2 sensor (sensor 2) malfunction	-	HO2 sensor (sensor 2) Gas leakage from exhaust system	C
      Lean / Rich	Rich	HO2 sensor (sensor 2) malfunction	-	HO2 sensor (sensor 2) Gas leakage from exhaust system	C
      Lean	Lean	Actual air-fuel ratio (A/F) lean	May occur	Extremely rich or lean actual A/F Gas leakage from exhaust system	A
      Rich	Rich	Actual A/F rich	-	Extremely rich or lean actual A/F Gas leakage from exhaust system	A

      Result: 

      DIAGNOSIS PROCEDURE
      
      

      Status O2S B1S1	Status O2S B1S2	A/F Condition and HO2 Sensors (sensors 1 and 2) Condition	Misfires	Main Suspected Trouble Areas	Proceed to
      Lean / Rich	Lean / Rich	Normal	-	TWC Gas leakage from exhaust system	A
      Lean	Lean / Rich	HO2 sensor (sensor 1) malfunction	-	HO2 sensor (sensor 1)	B
      Rich	Lean / Rich	HO2 sensor (sensor 1) malfunction	-	HO2 sensor (sensor 1)	B
      Lean / Rich	Lean	HO2 sensor (sensor 2) malfunction	-	HO2 sensor (sensor 2) Gas leakage from exhaust system	C
      Lean / Rich	Rich	HO2 sensor (sensor 2) malfunction	-	HO2 sensor (sensor 2) Gas leakage from exhaust system	C
      Lean	Lean	Actual air-fuel ratio (A/F) lean	May occur	Extremely rich or lean actual A/F Gas leakage from exhaust system	A
      Rich	Rich	Actual A/F rich	-	Extremely rich or lean actual A/F Gas leakage from exhaust system	A

      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.

   B : CHECK AND REPLACE OXYGEN SENSOR (SENSOR 1) 

   C : CHECK AND REPLACE HEATED OXYGEN SENSOR (SENSOR 2), OR 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 : GO TO NEXT STEP 

4. REPLACE THREE-WAY CATALYTIC CONVERTER (EXHAUST MANIFOLD) 
   NOTE: Replace both the front and rear catalysts (front exhaust pipe).