| 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, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, 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 voltage output of the heated oxygen sensor 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 heated oxygen sensor is long, the oxygen storage capacity is great. There is a direct correlation between the heated oxygen sensor 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.
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.
| 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). |
| Comes on (Euro-OBD) / - (Except Euro-OBD) | DTC stored (Euro-OBD) / - (Except Euro-OBD) | SAE Code: P0420 |
CATALYST LOCATION
| *1 | Air Fuel Ratio Sensor (Sensor 1) | *2 | Heated Oxygen Sensor (Sensor 2) |
| *3 | Exhaust Manifold Converter Sub-assembly | *4 | Front Exhaust Pipe Assembly |
| *5 | Center Exhaust Pipe Assembly | *6 | Tail Exhaust Pipe Assembly |
| *7 | TWC: Front Catalyst | *8 | TWC: Rear Catalyst |
Note
Replace the exhaust manifold converter sub-assembly (*3) and the center exhaust pipe assembly (*5) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor*1 and heated oxygen sensor*2)
MONITOR STRATEGY
| Required Sensors/Components (Main) | Air fuel ratio sensor Heated oxygen sensor |
| Required Sensors/Components (Related) | Intake air temperature sensor (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 | -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 status | Activated |
| Fuel system status | Closed loop |
| Engine load | 10% or higher, and less than 140% |
| All of the following conditions are met | - |
| Mass air flow rate | 3.0 to 40 gm/sec. |
| Front catalyst temperature (estimated) | 550°C (1022°F) to 800°C (1472°F) |
| Rear catalyst temperature (estimated) | 350°C (662°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.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: P042000.
Check the DTC judgment result.
GTS Display Description NORMAL
DTC judgment completed
System normal
ABNORMAL
DTC judgment completed
System abnormal
INCOMPLETE
DTC judgment not completed
Perform driving pattern after confirming DTC enabling conditions
N/A
Unable to perform DTC judgment
Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
Tech Tips
If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A and no pending DTC is 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, perform the following procedure.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: P042000.
Check the DTC judgment result.
GTS Display Description NORMAL
DTC judgment completed
System normal
ABNORMAL
DTC judgment completed
System abnormal
INCOMPLETE
DTC judgment not completed
Perform driving pattern after confirming DTC enabling conditions
N/A
Unable to perform DTC judgment
Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
Tech Tips
If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
CONDITIONING FOR SENSOR TESTING
Tech Tips
Perform the operation with the engine speeds and time durations described below prior to checking the waveforms of the air fuel ratio and heated oxygen sensors. This is to activate the sensors sufficiently to obtain appropriate inspection results.
Connect the GTS to the DLC3.
Turn the engine switch is on (IG) and turn the GTS on [A].
Start the engine and warm it up with all the accessories switched off until the engine coolant temperature stabilizes [B].
Enter the following menus: Powertrain / Engine / Data List / A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2.
Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes [C].
While running the engine at 3000 rpm for 2 seconds, and then 2000 rpm for 2 seconds, check the waveforms of the air fuel ratio and heated oxygen sensors using the GTS [D].
Tech Tips
If the voltage output of either the air fuel ratio or heated oxygen sensor does not fluctuate, or there is a noise in the waveform of either sensor, the sensor may be malfunctioning.
If the voltage outputs of both the sensors remain lean or rich, the air fuel ratio may be extremely lean or rich. In such cases, perform the Control the Injection Volume for A/F Sensor Active Test using the GTS.
If the Three-way Catalytic Converter (TWC) has deteriorated, the heated oxygen sensor (located behind the Three-way Catalytic Converter [TWC]) voltage output fluctuates up and down frequently, even under normal driving conditions (active air fuel ratio control is not performed).
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 inspection 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 CodesResult 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.
B 
GO TO DTC CHART Click here
A 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.
Run the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor / Data List / A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2.
Powertrain > Engine > Active TestActive Test Display Control the Injection Volume for A/F Sensor Data List Display A/F (O2) Sensor Voltage B1S1 O2 Sensor Voltage B1S2 Perform the Active Test with the engine idling (change the fuel injection volume).
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) displayed on the GTS.
Tech Tips
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
(Air fuel ratio)
12.5% Rich Below 3.1 V -12.5% Lean Higher than 3.4 V O2 Sensor Voltage B1S2
(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 Status of O2 Sensor Voltage B1S2 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
Lean: During Control the Injection Volume for A/F Sensor, the air fuel ratio sensor output voltage (A/F (O2) Sensor Voltage B1S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2 Sensor Voltage B1S2) is consistently less than 0.4 V.
Rich: During Control the Injection Volume for A/F Sensor, the A/F (O2) Sensor Voltage B1S1 is consistently less than 3.1 V, and the O2 Sensor Voltage B1S2 is consistently higher than 0.55 V.
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.
B REPLACE AIR FUEL RATIO SENSOR Click here
C CHECK FOR EXHAUST GAS LEAK Click here
D CHECK FOR EXHAUST GAS LEAK Click here
A CHECK FOR EXHAUST GAS LEAK
Check for exhaust gas leaks.
OK No gas leaks. Result Proceed to OK NG
OK GO TO STEP 11 Click here
NG GO TO STEP 9 Click here
REPLACE AIR FUEL RATIO SENSOR
Replace the air fuel ratio sensor.
Click here
Tech Tips
Perform "Inspection After Repair" after replacing the air fuel ratio sensor.
Click here
Result Proceed to NEXT
NEXT GO TO STEP 10 Click here
CHECK FOR EXHAUST GAS LEAK
Check for exhaust gas leaks.
OK No gas leaks. Result Proceed to OK NG
NG GO TO STEP 9 Click here
OK REPLACE HEATED OXYGEN SENSOR
Replace the heated oxygen sensor.
Click here
Result Proceed to NEXT
NEXT GO TO STEP 10 Click here
CHECK FOR EXHAUST GAS LEAK
Check for exhaust gas leaks.
OK No gas leaks. Result Proceed to OK NG
NG REPAIR OR REPLACE EXHAUST GAS LEAK POINT Click here
OK 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 and P017200 Inspection Procedure.
Click here
Result Proceed to NEXT
NEXT GO TO STEP 10 Click here
REPAIR OR REPLACE EXHAUST GAS LEAK POINT
Repair or replace the exhaust gas leak point.
Tech Tips
Perform "Inspection After Repair" after repairing or replacing the exhaust system.
Click here
Result Proceed to NEXT
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 DTCsTurn 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 CodesResult Result Proceed to DTC P042000 is output A DTCs are not output
(No pending DTCs output)
B
B END
A REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST)
Note
Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst) and the center exhaust pipe assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.
Tech Tips
Confirm the replacement parts, referring to the illustration in Catalyst Location.
Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst).
Click here
Replace the center exhaust pipe assembly (TWC: Rear catalyst).
Click here
Result Proceed to NEXT
NEXT END
