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 15 to 20 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 illuminates the MIL and sets the DTC.
DTC No. |
DTC Detection Condition |
Trouble Area |
---|---|---|
P0420 |
The oxygen storage capacity value is less than the standard value under active air fuel ratio control (1 trip detection logic). |
|
CATALYST LOCATION
Text in Illustration
*1 |
Exhaust Manifold Converter Sub-assembly (TWC: Front Catalyst) |
*2 |
Air Fuel Ratio Sensor (Sensor 1) |
*3 |
Heated Oxygen Sensor (Sensor 2) |
*4 |
Front Exhaust Pipe Assembly |
*5 |
Canter Exhaust Pipe Assembly (TWC: Rear Catalyst) |
*6 |
Tail Exhaust Pipe Assembly |
NOTICE:
Replace the exhaust manifold converter sub-assembly (*1) and the center exhaust pipe assembly (*5) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor *2 and heated oxygen sensor *3)
MONITOR STRATEGY
Related DTCs |
P0420: Catalyst Deterioration |
Required Sensors/Components (Main) |
Air fuel ratio sensor Heated oxygen sensor |
Required Sensors/Components (Related) |
Intake air temperature sensor Mass air flow meter Crankshaft position sensor Engine coolant temperature sensor |
Frequency of Operation |
Once per driving cycle |
Duration |
Approximately 30 seconds |
MIL Operation |
Immediately |
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
Monitor runs whenever following DTCs not stored |
P0010 (Camshaft Timing Oil Control Valve) P0011 (VVT System - Advance) P0012 (VVT System - Retard) P0016 (VVT System - Misalignment) P0013 (Exhaust Camshaft Timing Oil Control Valve) P0014 (Exhaust VVT System - Advance) P0015 (Exhaust VVT System - Retard) P0017 (Exhaust VVT System - Misalignment) P0031, P0032, P101D (Air Fuel Ratio Sensor Heater) P0037, P0038, P102D (Heated Oxygen Sensor Heater) P014C, P014D, P015A, P015B, P2195, P2196, P2237, P2238, P2239, P2252, P2253 (Air Fuel Ratio Sensor) P0136, P0137, P0138, P0139, P013A, P0607 (Rear Oxygen Sensor) P0102, P0103 (Mass Air Flow Meter) P0115, P0117, P0118 (Engine Coolant Temperature Sensor) P0125 (Insufficient Coolant Temperature for Closed Loop Fuel Control) P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle Position Sensor) P0171, P0172 (Fuel System) P0300 - P0304 (Misfire) P0335 (Crankshaft Position Sensor) P0340, P0342, P0343 (Camshaft Position Sensor) P0365, P0367, P0368 (Exhaust Camshaft Position Sensor) P0351 - P0354 (Igniter) P0500 (Vehicle Speed Sensor) P219A, P219C, P219D, P219E, P219F (Air Fuel Ratio Imbalance) |
Response rate during fuel cut from rich condition |
Completed |
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) [(570 mmHg(abs)] or higher |
Idling |
OFF |
Engine speed |
Less than 3000 rpm |
Air fuel ratio sensor status |
Activated |
Fuel system status |
Closed loop |
Engine load |
10% or more, and less than 90% |
All of the following conditions are met |
Condition 1, 2 and 3 |
1. Mass air flow rate |
2.5 gm/sec or more, and less than 70 gm/sec |
2. Front catalyst temperature (estimated) |
615°C (1139°F) or more, and less than 840°C (1544°F) |
3. Rear catalyst temperature (estimated) |
430°C (806°F) or more, and less than 770°C (1418°F) |
Shift position |
3rd or higher |
TYPICAL MALFUNCTION THRESHOLDS
Oxygen Storage Capacity (OSC) of catalyst (Normalized) |
Less than 1 |
MONITOR RESULT
Refer to Checking Monitor Status (See page
).
CONFIRMATION DRIVING PATTERN
HINT:
HINT:
In order to keep the idling stable, turn off the A/C and all other electric loads and do not perform any shift operations.
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT:
Drive the vehicle while keeping the engine load as constant as possible.
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT:
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT:
HINT:
If the monitor item does not change to Complete, and no DTCs are stored, perform the following procedure.
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
HINT:
HINT:
If the monitor item does not change to Complete, and no DTCs are stored, extend the driving time.
HINT:
CONDITIONING FOR SENSOR TESTING
HINT:
Perform the operation with the engine speeds and time durations described below prior to checking the waveforms of the air fuel ratio sensor and heated oxygen sensor. This is to activate the sensors sufficiently to obtain the appropriate inspection results.
HINT:
CAUTION / NOTICE / HINT
HINT:
PROCEDURE
1. |
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine / Trouble Codes.
(e) Read the DTCs.
Result |
Proceed to |
---|---|
DTC P0420 is output |
A |
DTC P0420 and other DTCs are output |
B |
HINT:
If any DTCs other than P0420 are output, troubleshoot those DTCs first.
B |
GO TO DTC CHART |
|
2. |
PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME) |
(a) Connect the Techstream to the DLC3.
(b) Start the engine and warm it up.
(c) Turn the Techstream on.
(d) Run the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(e) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume.
(f) Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
(g) Monitor the voltage outputs of the air fuel ratio sensor and heated oxygen sensor (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.
HINT:
Standard:
Techstream Display (Sensor) |
Injection Volume |
Status |
Voltage |
---|---|---|---|
AFS Voltage B1S1 (Air fuel ratio) |
+12% |
Rich |
Below 3.1 V |
-12% |
Lean |
Higher than 3.4 V |
|
O2S B1S2 (Heated oxygen) |
+12% |
Rich |
Higher than 0.55 V |
-12% |
Lean |
Below 0.4 V |
Status AFS Voltage B1S1 |
Status O2S B1S2 |
Air Fuel Ratio Condition and Air Fuel Ratio and Heated Oxygen Sensors Condition |
Misfire |
Main Suspected Trouble Area |
Proceed to |
---|---|---|---|---|---|
Lean/Rich |
Lean/Rich |
Normal |
- |
|
A |
Lean |
Lean/Rich |
Air fuel ratio sensor malfunction |
- |
|
B |
Rich |
Lean/Rich |
Air fuel ratio sensor malfunction |
- |
|
|
Lean/Rich |
Lean |
Heated oxygen sensor malfunction |
- |
|
C |
Lean/Rich |
Rich |
Heated oxygen sensor malfunction |
- |
|
|
Lean |
Lean |
Actual air fuel ratio lean |
May occur |
|
D |
Rich |
Rich |
Actual air fuel ratio rich |
- |
|
Lean: During Control the Injection Volume, the air fuel ratio sensor output voltage (AFS Voltage B1S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2) is consistently below 0.4 V.
Rich: During Control the Injection Volume, the AFS Voltage B1S1 is consistently below 3.1 V, and the O2S B1S2 is consistently higher than 0.55 V.
Lean/Rich: During Control the Injection Volume of the Active Test, the output voltage of the heated oxygen sensor alternates correctly.
B |
GO TO STEP 5 |
C |
GO TO STEP 6 |
D |
GO TO STEP 8 |
|
3. |
CHECK FOR EXHAUST GAS LEAK |
(a) Check for exhaust gas leaks.
OK:
No gas leaks.
NG |
GO TO STEP 10 |
|
4. |
REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST)) |
NOTICE:
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.
HINT:
Confirm the replacement parts, referring to the illustration in the Catalyst Location.
(a) Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst) (See page ).
(b) Replace the center exhaust pipe assembly (TWC: Rear catalyst) (See page ).
NEXT |
END |
5. |
REPLACE AIR FUEL RATIO SENSOR |
(a) Replace the air fuel ratio sensor (See page ).
HINT:
Perform "Inspection After Repair" after replacing the air fuel ratio sensor (See page ).
NEXT |
GO TO STEP 11 |
6. |
CHECK FOR EXHAUST GAS LEAK |
(a) Check for exhaust gas leaks.
OK:
No gas leaks.
NG |
GO TO STEP 10 |
|
7. |
REPLACE HEATED OXYGEN SENSOR |
(a) Replace the heated oxygen sensor (See page ).
HINT:
Perform "Inspection After Repair" after replacing the heated oxygen sensor (See page ).
NEXT |
GO TO STEP 11 |
8. |
CHECK FOR EXHAUST GAS LEAK |
(a) Check for exhaust gas leaks.
OK:
No gas leaks.
NG |
GO TO STEP 10 |
|
9. |
CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO |
(a) Check the cause of extremely rich or lean actual air fuel ratio, referring to DTC P0171 Inspection Procedure (See page ).
NEXT |
GO TO STEP 11 |
10. |
REPAIR OR REPLACE EXHAUST GAS LEAK POINT |
(a) Repair or replace exhaust gas leak point.
HINT:
Perform "Inspection After Repair" after repairing or replacing the exhaust system (See page ).
|
11. |
CHECK WHETHER DTC OUTPUT RECURS (DTC P0420) |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Clear the DTCs (See page ).
(e) Turn the ignition switch off and wait for at least 30 seconds.
(f) Turn the ignition switch to ON.
(g) Turn the Techstream on.
(h) Start the engine.
(i) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(j) Enter the following menus: Powertrain / Engine / Trouble Codes.
(k) Read the DTCs.
Result
Result |
Proceed to |
---|---|
DTC P0420 is output |
A |
DTC is not output (No pending DTCs output) |
B |
B |
END |
|
12. |
REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND FRONT EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST)) |
NOTICE:
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.
HINT:
Confirm the replacement parts, referring to the illustration in the Catalyst Location.
(a) Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst) (See page ).
(b) Replace the center exhaust pipe assembly (TWC: Rear catalyst) (See page ).
NEXT |
END |
Reassembly
REASSEMBLY
PROCEDURE
1. PRECAUTION
NOTICE:
After turning the ignition switch off, waiting time may be required before disconnecting
the cable from the negative (-) battery terminal. Therefore, make sure to read the
disconnecting the cable from the nega ...
Removal
REMOVAL
PROCEDURE
1. REMOVE REAR BUMPER ASSEMBLY
(See page )
2. REMOVE ULTRASONIC SENSOR CLIP
(a) Disconnect the connector.
Text in Illustration
*A
LH Side
*B
...
Checking and replacing fuses
If any of the electrical components do not operate, a fuse may have blown.
If this happens, check and replace the fuses as necessary.
Vehicles with smart key system:
Turn the “ENGINE START STOP” switch off.
Vehicles without smart key system:
Turn th ...