SFI SYSTEM(w/ GPF), Diagnostic DTC:P042000

DTC Code	DTC Name
P042000	Catalyst System Efficiency Below Threshold Bank 1

MONITOR DESCRIPTION

The ECM uses sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to monitor its efficiency.

The first sensor, the air fuel ratio sensor (sensor 1), sends pre-catalyst information to the ECM. The second sensor, the air fuel ratio sensor (sensor 2), sends post-catalyst information to the ECM.

In order to detect any deterioration in the three-way catalytic converter, the ECM calculates the oxygen storage capacity of the three-way catalytic converter. This calculation is based on the output current of the air fuel ratio sensor (sensor 2) while performing active air fuel ratio control.

The oxygen storage capacity value is an indication of the oxygen storage capacity of the three-way catalytic converter. When the vehicle is being driven with a warm engine, active air fuel ratio control is performed for approximately 30 seconds. When it is performed, the ECM deliberately sets the air fuel ratio to lean or rich levels. If the cycle of the waveform for the air fuel ratio sensor (sensor 2) is long, the oxygen storage capacity is great. There is a direct correlation between the air fuel ratio sensor (sensor 2) and the oxygen storage capacity of the three-way catalytic converter.

The ECM uses the oxygen storage capacity value to determine the state of the three-way catalytic converter. If any deterioration has occurred, the ECM will illuminate the MIL and store a DTC.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory	Note
P042000	Catalyst System Efficiency Below Threshold Bank 1	The oxygen storage capacity value is less than the standard value under active air fuel ratio control (2 trip detection logic).	Gas leak from exhaust system Air fuel ratio sensor (sensor 1) Air fuel ratio sensor (sensor 2) Exhaust manifold converter sub-assembly (TWC: Front catalyst) and front No. 2 exhaust pipe sub-assembly (TWC: Rear catalyst)	Comes on	DTC stored	SAE: P0420

This system determines the deterioration of the entire catalyst system (including the front and rear catalysts), by using the oxygen storage capacity value of the front catalyst, that is more sensitive than the rear catalyst, as the representative value. Therefore, be sure to replace the front and rear catalysts together when catalyst replacement is necessary.

CATALYST LOCATION

*1	Air Fuel Ratio Sensor (Sensor 1)	*2	Air Fuel Ratio Sensor (Sensor 2)
*3	Exhaust Manifold Converter Sub-assembly (TWC: Front Catalyst)	*4	Front Exhaust Pipe Sub-assembly
*5	Front No. 2 Exhaust Pipe Sub-assembly (TWC: Rear Catalyst)	*6	Center Exhaust Pipe Assembly
*7	Tail Exhaust Pipe Assembly	-	-

Note

Replace the exhaust manifold converter sub-assembly (*3) and the front No. 2 exhaust pipe sub-assembly (*5) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor (Sensor 1)*1 and air fuel ratio sensor (Sensor 2)*2)

MONITOR STRATEGY

Required Sensors/Components (Main)

Air fuel ratio sensor (Sensor 1)

Air fuel ratio sensor (Sensor 2)

Required Sensors/Components (Related)

Intake air temperature sensor (Built into mass air flow meter sub-assembly)

Mass air flow meter sub-assembly

Crankshaft position sensor

Engine coolant temperature sensor

Frequency of Operation

Once per driving cycle

TYPICAL ENABLING CONDITIONS

Battery voltage	11 V or higher
Intake air temperature (for mass air flow meter sub-assembly)	-10°C (14°F) or higher
Engine coolant temperature	75°C (167°F) or higher
Atmospheric pressure	76 kPa(abs) [11.02 psi(abs)] or higher
Idling	Off
Engine speed	Less than 3200 rpm
Air fuel ratio sensor (sensor 1) status	Activated
Fuel system status	Closed loop
Engine load	10% or higher, and less than 140%
Shift position	4th or higher
All of the following conditions are met	-
Mass air flow rate	4.0 to 25 gm/sec.
Front catalyst temperature (estimated)	550°C (968°F) to 800°C (1472°F)
Rear catalyst temperature (estimated)	350°C (572°F) to 700°C (1292°F)

CONFIRMATION DRIVING PATTERN

Tech Tips

Performing this confirmation driving pattern will activate the catalyst efficiency monitor. This is very useful for verifying the completion of a repair.

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the engine switch off and wait for at least 30 seconds.
Turn the engine switch on (IG) and turn the GTS on.
Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [A].
Drive the vehicle at approximately 60 km/h (37 mph) for 10 minutes or more [B].

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

Tech Tips

Drive the vehicle while keeping the engine load as constant as possible.
Turn the engine switch off and wait for at least 30 seconds [C].
Turn the engine switch on (IG) and turn the GTS on.
Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [D].
Drive the vehicle at approximately 60 km/h (37 mph) for 10 minutes or more [E].

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

Tech Tips

Drive the vehicle while keeping the engine load as constant as possible.
Enter the following menus: Powertrain / Engine / Trouble Codes [F].
Read the pending DTCs.
Tech Tips
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
Drive the vehicle at a speed between 75 and 100 km/h (47 and 62 mph) for 10 minutes or more [G].

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

Tech Tips

Drive the vehicle while keeping the engine load as constant as possible.
Enter the following menus: Powertrain / Engine / Trouble Codes [H].
Read the pending DTCs.
Tech Tips
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, system is normal.

CAUTION / NOTICE / HINT

Tech Tips

If a malfunction cannot be found when troubleshooting DTC P042000, a lean or rich abnormality may be the cause. Perform troubleshooting by following the procedure for P017100 (System Too Lean) and P017200 (System Too Rich).
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.
Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P042000)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine / Trouble Codes.

Read the DTCs.

Powertrain > Engine > Trouble Codes

Result

Result	Proceed to
DTC P042000 is output	A
DTC P042000 and other DTCs are output	B

Tech Tips

If any DTCs other than P042000 are output, troubleshoot those DTCs first.

GO TO DTC CHART Click here

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

Connect the GTS to the DLC3.
Start the engine and warm it up.
Turn the GTS on.
Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.
Warm up the air fuel ratio sensors at an engine speed of 2500 rpm for 90 seconds.

Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor / Data List / A/F (O2) Sensor Current B1S1 and A/F (O2) Sensor Current B1S2.

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

Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).

Monitor the output current of the air fuel ratio sensor (A/F (O2) Sensor Current B1S1 and A/F (O2) Sensor Current B1S2) displayed on the GTS.

Tech Tips

Change the fuel injection volume within the range of -12.5% and +12.5%.
Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
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 voltage 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
A/F (O2) Sensor Current B1S1 (Air fuel ratio (sensor 1))	-12.5%	Lean	Higher than 0.037 mA
A/F (O2) Sensor Current B1S2 (Air fuel ratio (sensor 2))	+12.5%	Rich	Below -0.86 mA
A/F (O2) Sensor Current B1S2 (Air fuel ratio (sensor 2))	-12.5%	Lean	Higher 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)	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 rich or lean actual air fuel ratio Gas leak from exhaust system	D
Rich	Rich	Actual air fuel ratio rich	Extremely rich or lean actual air fuel ratio Gas leak from exhaust system	D

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 higher than 0.037 mA, and the air fuel ratio sensor (sensor 2) output currents (A/F (O2) Sensor Current B1S2) 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 is consistently below -0.075 mA, and the A/F (O2) Sensor Current B1S2 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.

REPLACE AIR FUEL RATIO SENSOR (SENSOR 1) Click here

CHECK FOR EXHAUST GAS LEAK Click here

CHECK FOR EXHAUST GAS LEAK

Check for exhaust gas leaks.

OK
No gas leaks.

Result

Proceed to
OK
NG

REPAIR OR REPLACE EXHAUST GAS LEAK POINT Click here

REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND FRONT NO. 2 EXHAUST PIPE SUB-ASSEMBLY (TWC: REAR CATALYST)

Note

Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst) and the front No. 2 exhaust pipe sub-assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.

Tech Tips

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

Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst).

Click here

Replace the front No. 2 exhaust pipe sub-assembly (TWC: Rear catalyst).

Click here

Result

Proceed to
NEXT

END

REPAIR OR REPLACE EXHAUST GAS LEAK POINT

Repair or replace exhaust gas leak point.

Tech Tips

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

Click here

Result

Proceed to
NEXT

CHECK WHETHER DTC OUTPUT RECURS (DTC P042000)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Clear the DTCs.

Powertrain > Engine > Clear DTCs
Turn the engine switch off and wait for at least 30 seconds.
Turn the engine switch on (IG).
Turn the GTS on.
Start the engine.
Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine / Trouble Codes.

Read the DTCs.

Powertrain > Engine > Trouble Codes

Result

Proceed to

DTC P042000 is output

DTC is not output

(No pending DTCs output)

END

REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND FRONT NO. 2 EXHAUST PIPE SUB-ASSEMBLY (TWC: REAR CATALYST)

Note

Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst) and the front No. 2 exhaust pipe sub-assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.

Tech Tips

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

Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst).

Click here

Replace the front No. 2 exhaust pipe sub-assembly (TWC: Rear catalyst).

Click here

Result

Proceed to
NEXT

END

REPLACE AIR FUEL RATIO SENSOR (SENSOR 1)

Replace the air fuel ratio sensor (Sensor 1).

Click here

Tech Tips

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

Click here

Result

Proceed to
NEXT

GO TO STEP 6 Click here

CHECK FOR EXHAUST GAS LEAK

Check for exhaust gas leaks.

OK
No gas leaks.

Result

Proceed to
OK
NG

GO TO STEP 5 Click here

REPLACE AIR FUEL RATIO SENSOR (SENSOR 2)

Replace the air fuel ratio sensor (Sensor 2).

Click here

Result

Proceed to
NEXT

GO TO STEP 6 Click here

CHECK FOR EXHAUST GAS LEAK

Check the exhaust gas leaks.

OK
No gas leaks.

Result

Proceed to
OK
NG

GO TO STEP 5 Click here

CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO

Check the cause of extremely rich or lean actual air fuel ratio, referring to the DTC P017100 Procedure.

Click here

Result

Proceed to
NEXT

GO TO STEP 6 Click here