DTC P0420-00: Catalyst System Efficiency Below Threshold Bank 1; DTC P0430-00: Catalyst System Efficiency Below Threshold Bank 2 [12/2023 - ]: Procedure

WARNING: This page is about a different car, the 2024 Lexus TX 550h+. However, it is still accessible from the selected car via links, so may be relevant.

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420-00 AND/OR P0430-00)

Read the DTCs.

Powertrain > Engine > Trouble Codes

Result

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

HINT:

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

Result:

GO TO DTC CHART. Refer To DIAGNOSTIC TROUBLE CODE CHART [12/2023 - ]

Result:

See step 2

READ FREEZE FRAME DATA (LONG FT B1S2 AND LONG FT B2S2)

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

HINT:

Refer to FREEZE FRAME DATA [12/2023 - ]

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

Tester Display
Long FT B1S2

Result

Result	Proceed to
The value of Long FT B1S2 is less than 1.0 %	A
The value of Long FT B1S2 is 1.0 % or more	B

Result:

See step 79

Result:

See step 3

CHECK PCV HOSE CONNECTIONS
OK

PCV valve and hose are connected correctly and are not damaged.

Result

Proceed to

OK

NG

Result:

OK

See step 5

Result:

NG

See step 4
REPAIR OR REPLACE PCV HOSE
Result

Proceed to

NEXT

Result:

NEXT

See step 5

PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)

Pre-procedure1

Put the engine in Inspection Mode (2WD for measuring Exhaust Gas).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

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

Idle the engine for 5 minutes or more with park (P) selected.

Change the fuel injection volume using the GTS, and monitor the output voltage of the air fuel ratio sensor (sensor 1) [A/F (O2) Sensor Current B1S1 or A/F (O2) Sensor Current B2S1] and air fuel ratio sensor (sensor 2) [A/F (O2) Sensor Current B1S2 or A/F (O2) Sensor Current B2S2] 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 B2S1
A/F (O2) Sensor Current B1S2
A/F (O2) Sensor Current B2S2

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) 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 value does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

Standard

GTS Display (Sensor)	Injection Volume	Status	Value
A/F (O2) Sensor Current B1S1 A/F (O2) Sensor Current B2S1 (Air fuel ratio (sensor 1))	12.5%	Rich	Below -0.075 mA
	-12.5%	Lean	Higher than 0.037 mA
A/F (O2) Sensor Current B1S2 A/F (O2) Sensor Current B2S2 (Air fuel ratio (sensor 2))	12.5%	Rich	Below -0.86 mA
	-12.5%	Lean	Higher than 0.33 mA

Result

Status of A/F (O2) Sensor Current B1S1 or A/F (O2) Sensor Current B2S1	Status of A/F (O2) Sensor Current B1S2 or A/F (O2) Sensor Current B2S2	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 EGR valve assembly	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)	B
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	C
Lean	Lean	Actual air fuel ratio lean	Extremely lean actual air fuel ratio Gas leak from exhaust system EGR valve assembly	D
Rich	Rich	Actual air fuel ratio rich	Extremely rich actual air fuel ratio Gas leak from exhaust system EGR valve assembly	D

Lean: During the Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor (sensor 1) output voltages (A/F (O2) Sensor Current B1S1 or A/F (O2) Sensor Current B2S1) is consistently higher than 0.037 mA, and the air fuel ratio sensor (sensor 2) output currents (A/F (O2) Sensor Current B1S2 or A/F (O2) Sensor Current B2S2) is consistently higher than 0.33 mA.
Rich: During the Control the Injection Volume for A/F Sensor Active Test, the A/F (O2) Sensor Current B1S1 or A/F (O2) Sensor Current B2S1 is consistently below -0.075 mA, and the A/F (O2) Sensor Current B1S2 or A/F (O2) Sensor Current B2S2 is consistently below -0.86 mA.
Lean/Rich: During the Control the Injection Volume for A/F Sensor Active Test, the output value of the air fuel ratio sensor (sensor 1) or air fuel ratio sensor (sensor 2) alternate correctly.

Post-procedure1

None.

Result:

See step 9

Result:

See step 10

Result:

See step 12

Result:

See step 6

CHECK FOR EXHAUST GAS LEAK

Check for exhaust gas leaks.

No gas leaks in exhaust system.

Result

Proceed to
OK
NG

Result:

See step 76

Result:

See step 7

PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)

Pre-procedure1

Put the engine in Inspection Mode (2WD for measuring Exhaust Gas).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

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

The A/C switch and all accessories should be off.

Confirm that the value of Data List item Engine Independent is "Operate" then check the value of Intake Manifold Absolute Pressure while performing the Active Test.

Powertrain > Engine > Active Test

Active Test Display
Control the EGR Step Position

Data List Display
Intake Manifold Absolute Pressure
Engine Independent

NOTE:

Make sure that the value of Data List item Engine Independent is "Operate" while performing the Active Test.
Do not leave the EGR valve open for 10 seconds or more during the Active Test.
Be sure to return the EGR valve to step 0 when the Active Test is completed.
Do not open the EGR valve 30 steps or more during the Active Test.

The value of Intake Manifold Absolute Pressure changes in response to the EGR step position when the value of Engine Independent is "Operate".

Standard

-	Control the EGR Step Position (Active Test)
-	0 Steps	0 to 30 Steps
Intake Manifold Absolute Pressure (Data List)	(EGR valve is fully closed)	Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed

HINT:

If the value of Data List item Engine Independent is "Not Opr" when the engine is idling, charge control is being performed. Perform the Active Test after charge control is complete ("Operate" is displayed).
While performing the Active Test, if the increase in the value of Intake Manifold Absolute Pressure is small, the EGR valve assembly may be malfunctioning.
Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of Intake Manifold Absolute Pressure may occur while performing the Active Test. However, the amount that the value of Intake Manifold Absolute Pressure increases will be smaller than normal.

Result

Result	Proceed to
Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed	A
None of the above conditions are met	B

Post-procedure1

None.

Result:

See step 83

Result:

See step 8

INSPECT EGR VALVE ASSEMBLY

Pre-procedure1

Remove the EGR valve assembly.
HINT:

Refer to REMOVAL [12/2023 - ]

Check if the EGR valve is stuck open.

EGR valve is tightly closed.

Result

Proceed to
OK
NG

Post-procedure1

None.

Result:

See step 83

Result:

REPLACE EGR VALVE ASSEMBLY. Refer to REMOVAL [12/2023 - ]

REPLACE AIR FUEL RATIO SENSOR (SENSOR 1)
HINT:

for Bank 1: Refer to REMOVAL [12/2023 - ]

for Bank 2: Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77

CHECK FOR EXHAUST GAS LEAK

Check for exhaust gas leaks.

No gas leaks in exhaust system.

Result

Proceed to
OK
NG

Result:

See step 76

Result:

See step 11

REPLACE AIR FUEL RATIO SENSOR (SENSOR 2)
HINT:

for Bank 1: Refer to REMOVAL [12/2023 - ]

for Bank 2: Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77

CHECK FOR EXHAUST GAS LEAK

Check for exhaust gas leaks.

No gas leaks in exhaust system.

Result

Proceed to
OK
NG

Result:

See step 76

Result:

See step 13

PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)

Pre-procedure1

Put the engine in Inspection Mode (2WD for measuring Exhaust Gas).

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

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

HINT:

The A/C switch and all accessories should be off.

Confirm that the value of Data List item Engine Independent is "Operate" then check the value of Intake Manifold Absolute Pressure while performing the Active Test.

Powertrain > Engine > Active Test

Active Test Display
Control the EGR Step Position

Data List Display
Intake Manifold Absolute Pressure
Engine Independent

NOTE:

Make sure that the value of Data List item Engine Independent is "Operate" while performing the Active Test.
Do not leave the EGR valve open for 10 seconds or more during the Active Test.
Be sure to return the EGR valve to step 0 when the Active Test is completed.
Do not open the EGR valve 30 steps or more during the Active Test.

The value of Intake Manifold Absolute Pressure changes in response to the EGR step position when the value of Engine Independent is "Operate".

Standard

-	Control the EGR Step Position (Active Test)
-	0 Steps	0 to 30 Steps
Intake Manifold Absolute Pressure (Data List)	(EGR valve is fully closed)	Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed

HINT:

If the value of Data List item Engine Independent is "Not Opr" when the engine is idling, charge control is being performed. Perform the Active Test after charge control is complete ("Operate" is displayed).
While performing the Active Test, if the increase in the value of Intake Manifold Absolute Pressure is small, the EGR valve assembly may be malfunctioning.
Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of Intake Manifold Absolute Pressure may occur while performing the Active Test. However, the amount that the value of Intake Manifold Absolute Pressure increases will be smaller than normal.

Result

Result	Proceed to
Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed	A
None of the above conditions are met	B

Post-procedure1

None.

Result:

See step 15

Result:

See step 14

INSPECT EGR VALVE ASSEMBLY

Pre-procedure1

Remove the EGR valve assembly.
HINT:

Refer to REMOVAL [12/2023 - ]

Check if the EGR valve is stuck open.

EGR valve is tightly closed.

Result

Proceed to
OK
NG

Post-procedure1

None.

Result:

REPLACE EGR VALVE ASSEMBLY. Refer to REMOVAL [12/2023 - ]

Result:

See step 15

PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION MODE)

Refer to PROCEDURE - Step 2

Result

Item		Proceed to
Port	Direct	Proceed to
OK	OK	A
OK	NG	B
NG	OK	C
NG	NG	D

Result:

See step 19

Result:

See step 35

Result:

See step 38

Result:

See step 16

CHECK IF VEHICLE HAS RUN OUT OF FUEL IN PAST

Refer to PROCEDURE - Step 3

Result

Result	Proceed to
YES	A
NO	B

Result:

See step 18

Result:

See step 17

DTC CAUSED BY RUNNING OUT OF FUEL

DTC caused by running out of fuel.

Result

Proceed to
NEXT

Result:

See step 77

CHECK FOR INTERMITTENT PROBLEMS
HINT:

Refer to CHECK FOR INTERMITTENT PROBLEMS [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77

READ VALUE USING GTS (FUEL PRESSURE (HIGH))

Refer to PROCEDURE - Step 4

Result

Result	Proceed to
The value of Fuel Pressure (High) is between 1800 and 2800 kPag	A
None of the above conditions are met	B

Result:

See step 29

Result:

See step 20

PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION MODE (DIRECT))

Refer to PROCEDURE - Step 5

Result

Item			Proceed to
High Pressure Fuel Pump Duty Ratio (D4)	Short FT B1S1 + Long FT B1S1	Short FT B2S1 + Long FT B2S1	Proceed to
10 to 40%	-	-	A
40% or higher	-20% or less	-20% or less	B
10% or less	+20% or higher	+20% or higher	B
40% or higher	+20% or higher	+20% or higher	C
10% or less	-20% or less	-20% or less	D

Result:

See step 26

Result:

See step 27

Result:

See step 28

Result:

See step 21

PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION MODE (DIRECT))

Refer to PROCEDURE - Step 6

Result

Item			Proceed to
High Pressure Fuel Pump Duty Ratio (D4)	Short FT B1S1 + Long FT B1S1	Short FT B2S1 + Long FT B2S1	Proceed to
10 to 40%	-25% or less	-25% or less	A
10 to 40%	-25% or less	-25 to +25%	B
10 to 40%	-25 to +25%	-25% or less	C
10 to 40%	+30% or higher	+30% or higher	A
10 to 40%	+25% or higher	-25 to +25%	B
10 to 40%	-25 to +25%	+25% or higher	C
10 to 40%	-25 to +25%	-25 to +25%	D

Result:

See step 23

Result:

See step 24

Result:

See step 25

Result:

See step 22

REPLACE DIRECT FUEL INJECTOR ASSEMBLY (ALL CYLINDERS)
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
REPLACE DIRECT FUEL INJECTOR ASSEMBLY (BANK 1)
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
REPLACE DIRECT FUEL INJECTOR ASSEMBLY (BANK 2)
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
CHECK FOR INTERMITTENT PROBLEMS
HINT:

Refer to CHECK FOR INTERMITTENT PROBLEMS [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
REPLACE FUEL DELIVERY PIPE WITH SENSOR ASSEMBLY LH (FUEL PRESSURE SENSOR (FOR HIGH PRESSURE SIDE))
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
REPLACE FUEL (ENGINE ROOM SIDE) PUMP ASSEMBLY (FOR HIGH PRESSURE SIDE)
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
REPLACE ECM
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77

CHECK MISFIRE COUNT OF DIRECT INJECTION

Refer to PROCEDURE - Step 7

Result

Injection Way	Misfire Count	Proceed to
Direct	No misfire counts, or misfire counts occur randomly in all cylinders	A
Direct	Misfire counts occur in particular cylinder	B

Result:

See step 34

Result:

See step 30

REPLACE FUEL (ENGINE ROOM SIDE) PUMP ASSEMBLY (FOR HIGH PRESSURE SIDE)
Refer to PROCEDURE - Step 8

Result

Proceed to

NEXT

Result:

NEXT

See step 31
CLEAR DTC
Refer to PROCEDURE - Step 9

Result

Proceed to

NEXT

Result:

NEXT

See step 32

CHECK WHETHER DTC OUTPUT RECURS (DTC P0420-00 OR P0430-00)

Pre-procedure1

Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

Read the pending DTCs.

Powertrain > Engine > Trouble Codes

Result

Result	Proceed to
P0420-00 or P0430-00 is output	A
DTCs are not output	B

Post-procedure1

None.

Result:

See step 77

Result:

See step 33

REPLACE ECM
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
REPLACE DIRECT FUEL INJECTOR ASSEMBLY
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
INSPECT PORT FUEL INJECTOR ASSEMBLY
Refer to PROCEDURE - Step 11

Result

Proceed to

OK

NG

Result:

NG

See step 37

Result:

OK

See step 36
REPLACE ECM
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
REPLACE PORT FUEL INJECTOR ASSEMBLY
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
CHECK PCV HOSE CONNECTIONS
Refer to PROCEDURE - Step 12

Result

Proceed to

OK

NG

Result:

NG

See step 75

Result:

OK

See step 39
CHECK INTAKE SYSTEM
Refer to PROCEDURE - Step 13

Result

Proceed to

OK

NG

Result:

NG

See step 74

Result:

OK

See step 40

PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)

Refer to PROCEDURE - Step 14

Result

Status A/F (O2) Sensor Current B1S1 or A/F (O2) Sensor Current B2S1	Status A/F (O2) Sensor Current B1S2 or A/F (O2) Sensor Current B2S2	Air Fuel Ratio Condition and Air Fuel Ratio Sensor (Sensor 1) Condition	Suspected Trouble Area	Proceed to
Lean/Rich	Lean/Rich	Normal	-	A
Lean	Lean	Actual air fuel ratio lean	PCV valve and hose PCV hose connections Gas leak from exhaust system Intake system Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor EGR valve assembly
Rich	Rich	Actual air fuel ratio rich	Gas leak from exhaust system Ignition system Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor EGR valve assembly
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)	B

Result:

See step 55

Result:

See step 41

READ VALUE USING GTS (COOLANT TEMPERATURE)
Refer to PROCEDURE - Step 15

Result

Proceed to

OK

NG

Result:

NG

See step 54

Result:

OK

See step 42

PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)

Refer to PROCEDURE - Step 16

Result

Result	Proceed to
Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed	A
None of the above conditions are met	B

Result:

See step 44

Result:

See step 43

INSPECT EGR VALVE ASSEMBLY
Refer to PROCEDURE - Step 17

Result

Proceed to

OK

NG

Result:

NG

See step 53

Result:

OK

See step 44

READ VALUE USING GTS (MASS AIR FLOW SENSOR)

Refer to PROCEDURE - Step 18

Result

Result	Proceed to
The value of Mass Air Flow Sensor is between 10.8 and 16.0 gm/sec	A
None of the above conditions are met	B

Result:

See step 62

Result:

See step 45

CHECK FUEL PRESSURE (FOR LOW PRESSURE SIDE)
Refer to PROCEDURE - Step 19

Result

Proceed to

OK

NG

Result:

NG

See step 50

Result:

OK

See step 46
CHECK FOR EXHAUST GAS LEAK
Refer to PROCEDURE - Step 20

Result

Proceed to

OK

NG

Result:

NG

See step 49

Result:

OK

See step 47
INSPECT IGNITION SYSTEM
Refer to PROCEDURE - Step 21

Result

Proceed to

OK

NG

Result:

OK

See step 62

Result:

NG

See step 48

REPAIR OR REPLACE IGNITION SYSTEM

Repair or replace ignition system.

Result

Proceed to
NEXT

Result:

See step 77

REPAIR OR REPLACE EXHAUST SYSTEM

Repair or replace exhaust system.

Result

Proceed to
NEXT

Result:

See step 77

CHECK FUEL LINE
Refer to PROCEDURE - Step 22

Result

Proceed to

OK

NG

Result:

NG

See step 52

Result:

OK

See step 51
GO TO FUEL PUMP CONTROL CIRCUIT
HINT:

Refer to Fuel Pump Control Circuit [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77

REPAIR OR REPLACE FUEL SYSTEM

Repair or replace fuel system.

Result

Proceed to
NEXT

Result:

See step 77

REPLACE EGR VALVE ASSEMBLY
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
REPLACE ENGINE COOLANT TEMPERATURE SENSOR
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77
INSPECT AIR FUEL RATIO SENSOR (SENSOR 1) (HEATER RESISTANCE)
Refer to PROCEDURE - Step 23

Result

Proceed to

OK

NG

Result:

NG

See step 73

Result:

OK

See step 56
CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR (SENSOR 1))
Refer to PROCEDURE - Step 24

Result

Proceed to

OK

NG

Result:

NG

See step 72

Result:

OK

See step 57
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)
Refer to PROCEDURE - Step 25

Result

Proceed to

OK

NG

Result:

NG

See step 70

Result:

OK

See step 58
REPLACE AIR FUEL RATIO SENSOR (SENSOR 1)
Refer to PROCEDURE - Step 26

Result

Proceed to

NEXT

Result:

NEXT

See step 59
CLEAR DTC
Refer to PROCEDURE - Step 27

Result

Proceed to

NEXT

Result:

NEXT

See step 60

CHECK WHETHER DTC OUTPUT RECURS (DTC P0420-00 OR P0430-00)

Pre-procedure1

Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

Read the pending DTCs.

Powertrain > Engine > Trouble Codes

Result

Result	Proceed to
P0420-00 or P0430-00 is output	A
DTCs are not output	B

Post-procedure1

None.

Result:

See step 77

Result:

See step 61

READ VALUE USING GTS (MASS AIR FLOW SENSOR)
Refer to PROCEDURE - Step 29

Result

Proceed to

NEXT

Result:

NEXT

See step 62
CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY CONNECTOR CONNECTION)
Refer to PROCEDURE - Step 30

Result

Proceed to

NEXT

Result:

NEXT

See step 63
CLEAR DTC
Refer to PROCEDURE - Step 31

Result

Proceed to

NEXT

Result:

NEXT

See step 64

CHECK WHETHER DTC OUTPUT RECURS (DTC P0420-00 OR P0430-00)

Pre-procedure1

Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

Read the pending DTCs.

Powertrain > Engine > Trouble Codes

Result

Result	Proceed to
P0420-00 or P0430-00 is output	A
DTCs are not output	B

Post-procedure1

None.

Result:

See step 77

Result:

See step 65

CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)
Refer to PROCEDURE - Step 33

Result

Proceed to

OK

NG

Result:

NG

See step 71

Result:

OK

See step 66
INSPECT MASS AIR FLOW METER SUB-ASSEMBLY
Refer to PROCEDURE - Step 34

Result

Proceed to

NEXT

Result:

NEXT

See step 67
CLEAR DTC
Refer to PROCEDURE - Step 35

Result

Proceed to

NEXT

Result:

NEXT

See step 68

CHECK WHETHER DTC OUTPUT RECURS (DTC P0420-00 OR P0430-00)

Pre-procedure1

Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

Read the pending DTCs.

Powertrain > Engine > Trouble Codes

Result

Result	Proceed to
P0420-00 or P0430-00 is output	A
DTCs are not output	B

Post-procedure1

None.

Result:

See step 77

Result:

See step 69

REPLACE ECM
HINT:

Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77

REPAIR OR REPLACE HARNESS OR CONNECTOR

Repair or replace harness or connector.

Result

Proceed to
NEXT

Result:

See step 77

REPAIR OR REPLACE HARNESS OR CONNECTOR

Repair or replace harness or connector.

Result

Proceed to
NEXT

Result:

See step 77

REPAIR OR REPLACE AIR FUEL RATIO SENSOR (SENSOR 1) POWER SOURCE CIRCUIT

Repair or replace air fuel ratio sensor (sensor 1) power source circuit.

Result

Proceed to
NEXT

Result:

See step 77

REPLACE AIR FUEL RATIO SENSOR (SENSOR 1)
HINT:

for Bank 1: Refer to REMOVAL [12/2023 - ]

for Bank 2: Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 77

REPAIR OR REPLACE INTAKE SYSTEM

Repair or replace intake system.

Result

Proceed to
NEXT

Result:

See step 77

REPAIR OR REPLACE PCV HOSE

Repair or replace pcv hose.

Result

Proceed to
NEXT

Result:

See step 77

REPAIR OR REPLACE EXHAUST SYSTEM

Repair or replace exhaust system.

HINT:

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

Refer to INITIALIZATION [12/2023 - ]

Result

Proceed to
NEXT

Result:

See step 77

CLEAR DTC

Pre-procedure1

None.

Clear the DTCs.

Powertrain > Engine > Clear DTCs

Result

Proceed to
NEXT

Post-procedure1

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

Result:

See step 78

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

Pre-procedure1

Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

Read the DTCs.

Powertrain > Engine > Trouble Codes

Result

Result	Proceed to
DTCs are not output	A
P0420-00 or P0430-00 is output	B

Post-procedure1

None.

Result:

END

Result:

See step 83

CHECK FOR EXHAUST GAS LEAK

Check for exhaust gas leaks.

No gas leaks in exhaust system.

HINT:

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

Refer to INITIALIZATION [12/2023 - ]

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE EXHAUST SYSTEM

Result:

See step 80

REPLACE AIR FUEL RATIO SENSOR (SENSOR 2)
HINT:

for Bank 1: Refer to REMOVAL [12/2023 - ]

for Bank 2: Refer to REMOVAL [12/2023 - ]

Result

Proceed to

NEXT

Result:

NEXT

See step 81

CLEAR DTC

Pre-procedure1

None.

Clear the DTCs.

Powertrain > Engine > Clear DTCs

Result

Proceed to
NEXT

Post-procedure1

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

Result:

See step 82

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

Pre-procedure1

Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

Read the DTCs.

Powertrain > Engine > Trouble Codes

Result

DTCs are not output.

Result

Proceed to
NEXT

Post-procedure1

None.

Result:

END

CHECK DTC OUTPUT (DTC P0420-00 AND/OR P0430-00)

HINT:

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

Read the DTCs.

Powertrain > Engine > Trouble Codes

Result

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

Result:

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

for Bank 1: Refer to REMOVAL [12/2023 - ]

for Bank 2: Refer to REMOVAL [12/2023 - ]

Result:

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

for Bank 1: Refer to REMOVAL [12/2023 - ]

for Bank 2: Refer to REMOVAL [12/2023 - ]

Result:

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

for Bank 1: Refer to REMOVAL [12/2023 - ]

for Bank 2: Refer to REMOVAL [12/2023 - ]