DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1); DTC P0430: Catalyst System Efficiency Below Threshold (Bank 2): Procedure

1. Connect Techstream to the DLC3.
2. Turn the engine switch on (IG) and turn the Techstream on.
3. Enter the following menus: Powertrain / Engine / Trouble Codes.
4. Read the DTCs.

   Result

   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 and/or P0430 are output, troubleshoot those DTCs first.

B → See step   13 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Start the engine and warm it up.
3. Turn the Techstream on.
4. Run the engine at an engine speed of 2500 rpm for approximately 90 seconds.
5. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume / AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2.
6. Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
7. Monitor the voltage outputs of the air fuel ratio sensor and heated oxygen sensor (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) displayed on the Techstream.

   HINT: 

   • Change the fuel injection volume within the range of - 12% to +12%. The injection volume can be changed in fine gradations.
   • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
   • The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
   • If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

   Standard

   Techstream Display (Sensor)	Injection Volume	Status	Voltage
   AFS Voltage B1S1 or AFS Voltage B2S1 (Air fuel ratio)	+12%	Rich	Below 3.1 V
   	-12%	Lean	Higher than 3.4 V
   O2S B1S2 or O2S B2S2 (Heated oxygen)	+12%	Rich	Higher than 0.55 V
   	-12%	Lean	Below 0.4 V

   Result

   Status AFS Voltage B1S1 or AFS Voltage B2S1	Status O2S B1S2 or O2S B2S2	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
   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
   Lean	Lean	Actual air-fuel ratio lean	May occur	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system	D
   Rich	Rich	Actual air-fuel ratio lean	-	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system

   • Lean: During Control the Injection Volume, the air fuel ratio sensor output voltage (AFS Voltage B1S1 or AFS Voltage B2S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2 or O2S B2S2) is consistently below 0.4 V.
   • Rich: During Control the Injection Volume, the AFS Voltage B1S1 or AFS Voltage B2S1 is consistently below 3.1 V, and the O2S B1S2 or O2S B2S2 is consistently higher than 0.55 V.
   • Lean/Rich: During Control the Injection Volume of the Active Test, the output voltage of the air fuel ratio sensor and heated oxygen sensor alternate correctly.

B → See step   7 

C → See step   5 

D → See step   6 

A: Go to next step 

1. Check for exhaust gas leaks.

   OK

   No gas leakage.

NG → See step   8 

OK: Go to next step 

HINT: 

Confirm the replacement parts, referring to the illustration in the Catalyst Location.

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Trouble Codes.
5. Read the DTCs.

   Result

   Result	Proceed to
   DTC P0420 is output	A, C
   DTC P0430 is output	B, C
   DTC P0420 and P0430 are output	A, B, C

A → See step   14 

B → See step   15 

C → See step   16 

1. Check for exhaust gas leaks.

   OK

   No gas leaks.

OK → See step   9 

NG → See step   8 

1. Check for exhaust gas leaks.

   OK

   No gas leaks.

OK → See step   10 

NG → See step   8 

1. Replace the air fuel ratio sensorRefer to REMOVAL .

NEXT → See step   11 

1. Repair or replace exhaust gas leak point.

NEXT → See step   11 

1. Replace the heated oxygen sensorRefer to REMOVAL .

NEXT → See step   11 

1. Check the cause of extremely rich or lean actual air fuel ratio, referring to the DTC P0171 Inspection ProcedureRefer to DTC P0171: System Too Lean (Bank 1); DTC P0172: System Too Rich (Bank 1); DTC P0174: System Too Lean (Bank 2); DTC P0175: System Too Rich (Bank 2) .

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCsRefer to DTC CHECK / CLEAR .
5. Turn the engine switch off and wait for at least 30 seconds.
6. Start the engine.
7. Turn the Techstream on.
8. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
9. Enter the following menus: Powertrain / Engine / Trouble Codes.
10. Read the pending DTCs.

    Result

    Result	Proceed to
    DTC P0420 and/or P0430 is output	A
    DTC is not output	B

B → END 

A: Go to next step 

HINT: 

Confirm the replacement parts, referring to the illustration in the Catalyst Location.

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Trouble Codes.
5. Read the DTCs.

   Result

   Result	Proceed to
   DTC P0420 is output	A, C
   DTC P0430 is output	B, C
   DTC P0420 and P0430 are output	A, B, C

A → See step   14 

B → See step   15 

C → See step   16