DTC P0420-00: Catalyst System Efficiency Below Threshold Bank 1 [11/2023 - ]: Procedure

1. Read the DTCs.

   Powertrain > Engine > Trouble Codes 

   Result

   Result	Proceed to
   DTC P0420-00 is output	A
   DTC P0420-00 and other DTCs are output	B

   HINT: 

   If any DTCs other than P0420-00 are output, troubleshoot those DTCs first.

Result: 

B 

GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [11/2023 - ] 

Result: 

A 

See step  2

1. Using the GTS, read the value displayed in the Freeze Frame Data.

   Powertrain > Engine > DTC (P0420-00) > Freeze Frame Data 

   Tester Display
   Long FT B1S2

   Result

   GTS Display	Result	Proceed to
   Long FT B1S2	Less than 1.0%	A
   	1.0% or higher	B

Result: 

B 

See step  14

Result: 

A 

See step  3

1. Start the engine and warm it up until the engine coolant temperature is 80°C (176°F) or higher.

   Powertrain > Engine > Data List 

   Tester Display
   Coolant Temperature

2. Warm up the air fuel ratio sensors at an engine speed of 2500 rpm for 90 seconds.
3. Change the fuel injection volume using the GTS, and monitor the output current of the air fuel ratio sensor (sensor 1) (A/F (O2) Sensor Current B1S1) and air fuel ratio sensor (sensor 2) (A/F (O2) Sensor Current B1S2) displayed on the GTS.

   Powertrain > Engine > Active Test 

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

   Data List Display
   A/F (O2) Sensor Current B1S1
   A/F (O2) Sensor Current B1S2

   HINT: 

   • The Active Test "Control the Injection Volume for A/F Sensor" can be used to lower the fuel injection volume by 12.5% or increase the injection volume by 12.5%.
   • The air fuel ratio sensor (sensor 1) is displayed as A/F (O2) Sensor Current B1S1, and the air fuel ratio sensor (sensor 2) is displayed as A/F (O2) Sensor Current B1S2 on the GTS.
   • The air fuel ratio sensor (sensor 1) has an output delay of a few seconds and the air fuel ratio sensor (sensor 2) has a maximum output delay of approximately 20 seconds.
   • If the sensor output current does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

   Standard

   GTS Display (Sensor)	Injection Volume	Status	Current
   A/F (O2) Sensor Current B1S1 (Air fuel ratio (sensor 1))	12.5%	Rich	Below -0.075 mA
   	-12.5%	Lean	More than 0.037 mA
   A/F (O2) Sensor Current B1S2 (Air fuel ratio (sensor 2))	12.5%	Rich	Below -0.86 mA
   	-12.5%	Lean	More than 0.33 mA

   Result

   Status A/F (O2) Sensor Current B1S1	Status A/F (O2) Sensor Current B1S2	Actual air fuel ratio, air fuel ratio sensor (sensor 1) and air fuel ratio sensor (sensor 2) 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 (sensor 1) malfunction	Air fuel ratio sensor (sensor 1)	B
   Rich	Lean/Rich	Air fuel ratio sensor (sensor 1) malfunction	Air fuel ratio sensor (sensor 1)
   Lean/Rich	Lean	Air fuel ratio sensor (sensor 2) malfunction	Air fuel ratio sensor (sensor 2) Gas leak from exhaust system	C
   Lean/Rich	Rich	Air fuel ratio sensor (sensor 2) malfunction	Air fuel ratio sensor (sensor 2) 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 the Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor (sensor 1) output current (A/F (O2) Sensor Current B1S1) is consistently more than 0.037 mA, and the air fuel ratio sensor (sensor 2) output current (A/F (O2) Sensor Current B1S2) is consistently more than 0.33 mA.
   2. Rich: During the Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor (sensor 1) output current (A/F (O2) Sensor Current B1S1) is consistently below -0.075 mA, and the air fuel ratio sensor (sensor 2) output current (A/F (O2) Sensor Current B1S2) is consistently below -0.86 mA.
   3. Lean/Rich: During the Control the Injection Volume for A/F Sensor Active Test, the output current of the air fuel ratio sensor (sensor 1) or air fuel ratio sensor (sensor 2) alternate correctly.

   HINT: 

   Refer to "Data List / Active Test" [A/F (O2) Sensor Current B1S1, A/F (O2) Sensor Current B1S2].

   Refer to DATA LIST / ACTIVE TEST [11/2023 - ]

Result: 

B 

See step  5

Result: 

C 

See step  6

Result: 

D 

See step  8

Result: 

A 

See step  4

1. Check for exhaust gas leaks.

   OK

   No gas leaks in exhaust system.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

See step  13

Result: 

NG 

See step  10

1. Replace the air fuel ratio sensor (sensor 1).

   Refer to REMOVAL [10/2022 - ]

   HINT: 

   Perform "Inspection After Repair" after replacing the air fuel ratio sensor (sensor 1).

   Refer to INITIALIZATION [10/2022 - ]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  11

1. Check for exhaust gas leaks.

   OK

   No gas leaks in exhaust system.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  10

Result: 

OK 

See step  7

1. Replace the air fuel ratio sensor (sensor 2).

   Refer to REMOVAL [10/2022 - ]

   HINT: 

   Perform "Inspection After Repair" after replacing the air fuel ratio sensor (sensor 2).

   Refer to INITIALIZATION [10/2022 - ]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  11

1. Check for exhaust gas leaks.

   OK

   No gas leaks in exhaust system.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  10

Result: 

OK 

See step  9

1. Check the cause of extremely rich or lean actual air fuel ratio, referring to the DTC P0171-00 and P0172-00 Inspection Procedure.

   Refer to DTC P0171-00: System Too Lean Bank 1; DTC P0172-00: System Too Rich Bank 1; DTC P1170-00: Fuel Performance/Port Injector; DTC P117B-00: Fuel Performance/Direct Injector [11/2023 - ]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  11

1. Repair or replace exhaust system.

   HINT: 

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

   Refer to INITIALIZATION [10/2022 - ]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  11

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  12

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	A
   DTC P0420-00 is output	B

Result: 

A 

END 

Result: 

B 

See step  13

Refer to REMOVAL [11/2023 - ]

Result

Result: 

NEXT 

END 

OK

No gas leaks in exhaust system.

HINT: 

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

Refer to INITIALIZATION [10/2022 - ]

Result

Result: 

NG 

REPAIR OR REPLACE EXHAUST SYSTEM 

Result: 

OK 

See step  15

Refer to REMOVAL [10/2022 - ]

HINT: 

Perform "Inspection After Repair" after replacing the air fuel ratio sensor (sensor 2).

Refer to INITIALIZATION [10/2022 - ]

Result

Result: 

NEXT 

See step  16

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  17

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

   Powertrain > Engine > Trouble Codes 

   Result

   DTCs are not output.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

END