Inspection Procedure

HINT:

Read freeze frame data using Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction (See FREEZE FRAME DATA ).

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420 AND/OR P0430) 
   1. Connect Techstream to the DLC3.
   2. Turn the engine switch on (IG) and turn the tester on.
   3. Enter the following menus: Powertrain / Engine / Trouble Code.
   4. Read the DTCs.

      Result 

      RESULT CHART
      
      

      Display (DTC output)	Proceed to
      P0420 and/or P0430	A
      P0420 and/or P0430 and other DTCs	B

      HINT:

      If any DTCs other than P0420 or P0430 are output, troubleshoot those DTCs first.

   B: GO TO DTC CHART  (See DIAGNOSTIC TROUBLE CODE CHART )

   A: Go to next step 

2. PERFORM ACTIVE TEST BY TECHSTREAM (A/F CONTROL) 
   1. Connect Techstream to the DLC3.
   2. Start the engine and turn the tester on.
   3. Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
   4. On the tester, enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F sensor.
   5. Perform the Control the Injection Volume for A/F Sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume.)
   6. Monitor the output voltages of the A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.

      HINT:

      • The Control the Injection Volume for A/F sensor 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.
        FUEL INJECTION VOLUME REFERENCE
        
        

        Tester Display (Sensor)	Injection Volume	Status	Voltage
        AFS B1 S1 or AFS B2 S1 (A/F)	+25 %	Rich	Less than 3.0 V
        AFS B1 S1 or AFS B2 S1 (A/F)	-12.5%	Lean	More than 3.35 V
        O2S B1 S2 or O2S B2 S2 (HO2)	+25 %	Rich	More than 0.55 V
        O2S B1 S2 or O2S B2 S2 (HO2)	-12 5 %	Lean	Less than 0.4 V

        Result 

        RESULT CHART
        
        

        Status AFS B1 S1 or AFS B2 S1	Status O2S B1 S2 or O2S B2 S2	A/F Condition and A/F and HO2 Sensor Conditions	Misfire	Main Suspected Trouble Areas	Proceed to
        Lean/Rich	Lean/Rich	Normal	-	Three-Way Catalytic Converter (TWC) Gas leakage from exhaust system	A
        Lean	Lean/Rich	A/F sensor malfunction	-	A/F sensor	B
        Rich	Lean/Rich	A/F sensor malfunction	May occur	A/F sensor	B
        Lean/Rich	Lean	HO2 sensor malfunction	-	HO2 sensor Gas leakage from exhaust system	C
        Lean/Rich	Rich	HO2 sensor malfunction	-	HO2 sensor Gas leakage from exhaust system	C
        Lean	Lean	Actual air-fuel ratio lean	May occur	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system	A
        Rich	Rich	Actual air-fuel ratio lean	-	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system	A
        Lean: During Control the Injection Volume for A/F sensor, the A/F sensor (AFS) output voltage is consistently more than 3.35 V, and the HO2 sensor output voltage (O2S) is consistently less than 0.4 V. Rich: During Control the Injection Volume for A/F sensor, the AFS is consistently less than 3.0 V, and the O2S is consistently more than 0.55 V. Lean/Rich: During Control the Injection Volume for A/F sensor of the Active Test, the output voltage of the HO2 sensor alternates correctly.

   B: CHECK AND REPLACE AIR FUEL RATIO SENSOR 

   C: CHECK AND REPLACE HEATED OXYGEN SENSOR, AND CHECK AND REPAIR EXHAUST GAS LEAKAGE 

   A: Go to next step 

3. CHECK FOR EXHAUST GAS LEAK 

   OK: 

   No gas leakage. 

   NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT 

   OK: Go to next step 

4. CHECK DTC OUTPUT (DTC P0420 AND/OR P0430) 
   1. Connect Techstream to the DLC3.
   2. Turn the engine switch on (IG) and turn the tester on.
   3. Enter the following menus: Powertrain / Engine / Trouble Code.
   4. Read the DTCs

      Result 

      RESULT CHART
      
      

      Display (DTC output)	Proceed to
      P0420	A
      P0430	B
      P0420 and P0430	A and B

   B:  Go to step  6

   A: Go to next step 

5. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY RH 
   1. Replace the exhaust manifold sub-assembly RH (See REMOVAL ).

   NEXT: REPLACE FRONT EXHAUST PIPE ASSEMBLY  (See REMOVAL )

6. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH 
   1. Replace the exhaust manifold sub-assembly LH (See REMOVAL ).

   NEXT: REPLACE FRONT EXHAUST PIPE ASSEMBLY  (See REMOVAL )