DTC P0420-00: Catalyst System Efficiency Below Threshold Bank 1; DTC P0430-00: Catalyst System Efficiency Below Threshold Bank 2 [12/2019 - 09/2020]: Procedure

1. Read the DTCs.

   Powertrain > Engine > Trouble Codes 

   Result

   Result	Proceed to
   DTC P0420-00 and/or P0430-00 are output	A
   DTC P0420-00 and/or P0430-00 and other DTCs are output	B

   HINT: 

   If any DTCs other than P0420-00 and/or P0430-00 are output, troubleshoot those DTCs first.

Result: 

B 

GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [12/2019 - 09/2020] 

Result: 

A 

See step  2

1. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.

   Powertrain > Engine > Data List 

   Tester Display
   Coolant Temperature

2. Warm up the air fuel ratio sensor at an engine speed of 2500 rpm for approximately 90 seconds.
3. Perform the Active Test operation with the engine idling (change the fuel injection volume).

   Powertrain > Engine > Active Test 

   Active Test Display
   Control the Injection Volume for A/F Sensor

   Data List Display
   A/F (O2) Sensor Voltage B1S1
   A/F (O2) Sensor Voltage B2S1
   O2 Sensor Voltage B1S2
   O2 Sensor Voltage B2S2

4. Monitor the voltage outputs of the air fuel ratio sensor and heated oxygen sensor (A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2 or A/F (O2) Sensor Voltage B2S1 and O2 Sensor Voltage B2S2) displayed on the GTS.

   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 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

   GTS Display (Sensor)	Injection Volume	Status	Voltage
   A/F (O2) Sensor Voltage B1S1 A/F (O2) Sensor Voltage B2S1 (Air fuel ratio)	12.5%	Rich	Below 3.1 V
   	-12.5%	Lean	Higher than 3.4 V
   O2 Sensor Voltage B1S2 O2 Sensor Voltage B2S2 (Heated oxygen)	12.5%	Rich	Higher than 0.55 V
   	-12.5%	Lean	Below 0.4 V

   Result

   Status of A/F (O2) Sensor Voltage B1S1 or A/F (O2) Sensor Voltage B2S1	Status of O2 Sensor Voltage B1S2 or O2 Sensor Voltage B2S2	Actual air fuel ratio, air fuel ratio sensor and heated oxygen sensor condition	Main Suspected Trouble Area	Proceed to
   Lean/Rich	Lean/Rich	Normal	Three-way catalytic converter Gas leak from exhaust system	A
   Lean	Lean/Rich	Air fuel ratio sensor malfunction	Air fuel ratio sensor	B
   Rich	Lean/Rich	Air fuel ratio sensor malfunction	Air fuel ratio sensor
   Lean/Rich	Lean	Heated oxygen sensor malfunction	Heated oxygen sensor Gas leak from exhaust system	C
   Lean/Rich	Rich	Heated oxygen sensor malfunction	Heated oxygen sensor Gas leak from exhaust system
   Lean	Lean	Actual air fuel ratio lean	Extremely lean actual air fuel ratio Gas leak from exhaust system	D
   Rich	Rich	Actual air fuel ratio rich	Extremely rich actual air fuel ratio Gas leak from exhaust system

   1. Lean: During Control the Injection Volume for A/F Sensor, the air fuel ratio sensor output voltage (A/F (O2) Sensor Voltage B1S1 or A/F (O2) Sensor Voltage B2S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2 Sensor Voltage B1S2 or O2 Sensor Voltage B2S2) is consistently less than 0.4 V.
   2. Rich: During Control the Injection Volume for A/F Sensor, the A/F (O2) Sensor Voltage B1S1 or A/F (O2) Sensor Voltage B2S1 is consistently less than 3.1 V, and the O2 Sensor Voltage B1S2 or O2 Sensor Voltage B2S2 is consistently higher than 0.55 V.
   3. Lean/Rich: During Control the Injection Volume for A/F Sensor of the Active Test, the output voltage of the air fuel ratio sensor or heated oxygen sensor alternates correctly.

Result: 

B 

See step  4

Result: 

C 

See step  5

Result: 

D 

See step  7

Result: 

A 

See step  3

1. Check for exhaust gas leaks.

   OK

   No gas leaks in exhaust system.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

See step  12

Result: 

NG 

See step  9

Refer to REMOVAL [12/2019 - 10/2022]

HINT: 

Perform "Inspection After Repair" after replacing the air fuel ratio sensor.

Refer to INITIALIZATION [12/2019 - 10/2022]

Result

Result: 

NEXT 

See step  10

1. Check for exhaust gas leaks.

   OK

   No gas leaks in exhaust system.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  9

Result: 

OK 

See step  6

Refer to REMOVAL [12/2019 - 10/2022]

HINT: 

Perform "Inspection After Repair" after replacing the heated oxygen sensor.

Refer to INITIALIZATION [12/2019 - 10/2022]

Result

Result: 

NEXT 

See step  10

1. Check the exhaust gas leaks.

   OK

   No gas leaks in exhaust system.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  9

Result: 

OK 

See step  8

1. Check the cause of extremely rich or lean actual air fuel ratio, referring to the DTC P0171-00 Inspection Procedure.

   Refer to DTC P0171-00: System Too Lean Bank 1; DTC P0172-00: System Too Rich Bank 1; DTC P0174-00: System Too Lean Bank 2; DTC P0175-00: System Too Rich Bank 2; DTC P1170-00: Fuel Performance/Port Injector; DTC P117B-00: Fuel Performance/Direct Injector [12/2019 - 10/2022]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  10

1. Repair or replace exhaust system.

   HINT: 

   Perform "Inspection After Repair" after repairing or replacing the exhaust system.

   Refer to INITIALIZATION [12/2019 - 10/2022]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  10

1. Clear the DTCs.

   Powertrain > Engine > Clear DTCs 

2. Turn the ignition switch off and wait for at least 30 seconds.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  11

1. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
2. Read the DTCs.

   Powertrain > Engine > Trouble Codes 

   Result

   Result	Proceed to
   DTCs are not output (No pending DTCs output)	A
   DTC P0420-00 and/or P0430-00 are output	B

Result: 

A 

END 

Result: 

B 

See step  12

HINT: 

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

1. Read the DTCs.

   Powertrain > Engine > Trouble Codes 

   Result

   Result	Proceed to
   DTC P0420-00 is output	A
   DTC P0430-00 is output	B
   DTC P0420-00 and P0430-00 are output	C

Result: 

A 

REPLACE EXHAUST MANIFOLD ASSEMBLY RH (TWC: FRONT CATALYST) AND CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) 

Refer to COMPONENTS [12/2019 - 10/2022]

Refer to COMPONENTS [12/2019 - 09/2020]

Result: 

B 

REPLACE EXHAUST MANIFOLD ASSEMBLY LH (TWC: FRONT CATALYST) AND CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) 

Refer to COMPONENTS [12/2019 - 10/2022]

Refer to COMPONENTS [12/2019 - 09/2020]

Result: 

C 

REPLACE EXHAUST MANIFOLD ASSEMBLY RH (TWC: FRONT CATALYST), EXHAUST MANIFOLD ASSEMBLY LH (TWC: FRONT CATALYST) AND CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) 

Refer to COMPONENTS [12/2019 - 10/2022]

Refer to COMPONENTS [12/2019 - 09/2020]