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

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG) and turn the Techstream ON.
3. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
4. Read 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 or P0430 are output, troubleshoot those DTCs first.

B → See step   5 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Put the engine in inspection mode. Refer to INSPECTION MODE PROCEDURE [09/2012 - ] .
3. Turn the Techstream ON.
4. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
6. Perform the Control the Injection Volume for A/F Sensor operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
7. Monitor the voltage outputs of the A/F and HO2 sensors (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 -12.5% to +12.5%.
   • 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

     Tester Display (Sensor)	Injection Volume	Status	Voltage
     AFS Voltage B1S1 or AFS Voltage B2S1 (A/F)	+12.5%	Rich	Less than 3.1 V
     AFS Voltage B1S1 or AFS Voltage B2S1 (A/F)	-12.5%	Lean	More than 3.4 V
     O2S B1S2 or O2S B2S2 (HO2)	+12.5%	Rich	More than 0.55 V
     O2S B1S2 or O2S B2S2 (HO2)	-12.5%	Lean	Less than 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 Sensors Conditions	Main Suspected Trouble Area	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	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	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system	A
     Rich	Rich	Actual air-fuel ratio rich	Extremely rich or lean actual air-fuel ratio Gas leakage from exhaust system

     Lean: During Control the Injection Volume for A/F Sensor, the A/F sensor output voltage (AFS) is consistently more than 3.4 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 3.1 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.

   • 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.

B → See step   6 

C → See step   7 

A: Go to next step 

OK

No gas leakage.

NG → REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT 

OK: Go to next step 

1. According to the DTCs output in the Check Any Other DTCs Output step, proceed to the next step according to the table below.
   RESULT
   
   

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

A → See step   8 

B → See step   10 

C → See step   9