- Three-way catalytic converter
- Gas leak from exhaust system
| Last Modified: 05-13-2024 | 6.11:8.1.0 | Doc ID: RM100000001GHBH |
| Model Year Start: 2020 | Model: Corolla | Prod Date Range: [01/2019 - 03/2019] |
| Title: 2ZR-FAE (ENGINE CONTROL): SFI SYSTEM: P0420; Catalyst System Efficiency Below Threshold (Bank 1); 2020 MY Corolla [01/2019 - 03/2019] | ||
|
DTC |
P0420 |
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 |
|---|---|---|---|---|---|
|
P0420 |
Catalyst System Efficiency Below Threshold (Bank 1) |
The oxygen storage capacity value is less than the standard value under active air fuel ratio control (1 trip detection logic). |
|
Comes on |
DTC stored |
CATALYST LOCATION
|
*1 |
Air Fuel Ratio Sensor |
*2 |
Heated Oxygen Sensor |
|
*3 |
Exhaust Manifold |
*4 |
TWC: Front Catalyst |
|
*5 |
TWC: Rear Catalyst |
*6 |
Front Exhaust Pipe Assembly |
|
*7 |
Tail Exhaust Pipe Assembly |
- |
- |
NOTICE:
Replace the front exhaust pipe assembly (*6) when catalyst replacement is necessary. (Excluding heated oxygen sensor (*2))
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 sub-assembly Crank position sensor Engine coolant temperature sensor |
|
Frequency of Operation |
Once per driving cycle |
|
Duration |
Approximately 30 seconds |
|
MIL Operation |
Immediate |
|
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
|
Monitor runs whenever the following DTCs are not stored |
P0010 (Camshaft timing oil control valve) P0011 (VVT system - advance) P0012 (VVT system - retard) P0013 (Exhaust camshaft timing oil control valve) P0014 (Exhaust VVT system - advance) P0015 (Exhaust VVT system - retard) P0016 (VVT system - misalignment) P0017 (Exhaust VVT system - misalignment) P0031, P0032 (Air fuel ratio sensor heater) P0037, P0038 (Heated oxygen sensor heater) P0102, P0103 (Mass air flow meter) P0107, P0108 (Manifold absolute pressure) P0115, P0117, P0118 (Engine coolant temperature sensor) P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle position sensor) P0125 (Insufficient coolant temperature for closed loop fuel control) P0136, P0137, P0138, P0139, P013A, P0607 (Heated oxygen sensor) P014C, P014D, P015A, P015B, P2195, P2196, P2237, P2238, P2239, P2252, P2253 (Air fuel ratio sensor) P0171, P0172 (Fuel system) P0300, P0301, P0302, P0303, P0304 (Misfire) P0335 (Crank position sensor) P0340, P0342, P0343 (Cam position sensor) P0365, P0367, P0368 (Exhaust cam position sensor) P0500 (Vehicle speed sensor) P219A, P219C, P219D, P219E, P219F (Air-fuel ratio imbalance) P264A, P2646, P2647, P1055, P10A0, P2648, P2649, P1049, P104A, U011B (Rocker arm control module) |
|
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 |
73°C (163.4°F) or higher |
|
Atmospheric pressure |
76 kPa(abs) [11 psi(abs)] or higher |
|
Idling |
Off |
|
Engine speed |
Less than 4000 rpm |
|
Air fuel ratio sensor status |
Activated |
|
Fuel system status |
Closed loop |
|
Engine load |
10% or higher, and less than 80% |
|
All of the following conditions are met |
1, 2 and 3 |
|
1. Mass air flow |
2.5 gm/sec or more, and less than 40 gm/sec |
|
2. Front catalyst temperature (estimated) |
600°C (1112°F) or higher, and less than 840°C (1544°F) (for CVT models) 630°C (1166°F) or higher, and less than 840°C (1544°F) (for Manual Transaxle models) |
|
3. Rear catalyst temperature (estimated) |
400°C (752°F) or higher, and less than 780°C (1436°F) |
|
Shift position |
3rd or higher (for CVT models) 4th or higher (for Manual Transaxle models) |
TYPICAL MALFUNCTION THRESHOLDS
|
Oxygen Storage Capacity (OSC) of catalyst (Normalized) |
Less than 1 |
MONITOR RESULT
Refer to detailed information in Checking Monitor Status.
Click here
![2020 - 2023 MY Corolla [01/2019 - 11/2022]; 2ZR-FAE (ENGINE CONTROL): SFI SYSTEM: CHECKING MONITOR STATUS](/t3Portal/stylegraphics/info.gif)
P0420: Catalyst Efficiency / O2 STORAGE B1
|
Monitor ID |
Test ID |
Scaling |
Unit |
Description |
|---|---|---|---|---|
|
$21 |
$AF |
Multiply by 0.001 |
No dimension |
Oxygen storage capacity of catalyst bank 1 (Normalized) |
CONFIRMATION DRIVING PATTERN
HINT:
- It is necessary that the response of the heated oxygen sensor is normal in order to confirm DTC P0420. Therefore, perform the driving pattern for the heated oxygen sensor monitor before performing the drive pattern for the catalyst efficiency monitor.
- Performing this confirmation driving pattern will activate the catalyst efficiency monitor. This is very useful for verifying the completion of a repair.
- Connect the Techstream to the DLC3.
- Turn the ignition switch to ON.
- Turn the Techstream on.
- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
- Turn the ignition switch off and wait for at least 30 seconds.
- Turn the ignition switch to ON.
- Turn the Techstream on.
- Enter the following menus: Powertrain / Engine and ECT / Monitor / Current Monitor.
- Check that Catalyst Efficiency / Current is Incomplete.
-
Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher with the shift lever in P or neutral [A].
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.
-
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.
HINT:
Drive the vehicle while keeping the engine load as constant as possible.
-
With the shift lever in B or 2nd gear, drive the vehicle at 60 km/h (37 mph), and then decelerate the vehicle by releasing the accelerator pedal for 5 seconds or more to perform the fuel-cut [C].
CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
- Enter the following menus: Powertrain / Engine and ECT / Monitor / Current Monitor / O2 Sensor / RL F/C B1S2 [D].
-
Check the Test Value for RL F/C B1S2.
HINT:
- If Test Value displays a value larger than 0, perform the following procedure, as the O2 sensor monitor is finished.
- If Test Value displays 0, perform step [C] until it displays a value larger than 0, as the O2 sensor monitor is not finished.
- Turn the ignition switch off and wait for at least 30 seconds [F].
- Turn the ignition switch to ON and turn the Techstream on.
- Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [G].
-
Drive the vehicle at approximately 60 km/h (37 mph) for 10 minutes or more [H].
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.
- The monitor item will change to Complete as the Catalyst Efficiency monitor operates.
- Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [I].
-
Check if any DTCs are stored.
HINT:
If the monitor item does not change to Complete, and no DTCs are stored, perform the following procedure.
-
Drive the vehicle at a speed between 75 and 100 km/h (47 and 63 mph) for 10 minutes or more [J].
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.
- The monitor item will change to Complete as the Catalyst Efficiency monitor operates.
- Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [K].
-
Check if any DTCs are stored.
HINT:
If the monitor item does not change to Complete, and no DTCs are stored, extend the driving time.
-
If no DTC is output, perform a universal trip and check for permanent DTCs.
Click here
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
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 and heated oxygen sensors. This is to activate the sensors sufficiently to obtain appropriate inspection results.
- Connect the Techstream to the DLC3.
- Start the engine and warm it up with all the accessories switched off until the engine coolant temperature stabilizes. [A]
- Turn the Techstream on.
- Enter the following menus: Powertrain / Engine and ECT / Data List / AFS Voltage B1S1 and O2S B1S2.
- Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes. [B]
- While running the engine at 3000 rpm for 2 seconds and 2000 rpm for 2 seconds, check the waveforms of the air fuel ratio and heated oxygen sensors using the Techstream. [C]
HINT:
- 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 Techstream.
- 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
HINT:
- If a malfunction cannot be found when troubleshooting DTC P0420, a lean or rich abnormality may be the cause. Perform troubleshooting by following the inspection procedure for P0171 (System Too Lean), and P0172 (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 Techstream. 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
|
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 and ECT / Trouble Codes.
(e) Read the DTCs.
Powertrain > Engine and ECT > Trouble Codes
|
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 |
|
|
|
2. |
PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME FOR A/F SENSOR) |
(a) Connect the Techstream to the DLC3.
(b) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.
(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 and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / Coolant Temp, AFS Voltage B1S1 and O2S B1S2.
Powertrain > Engine and ECT > Active Test
|
Active Test Display |
|---|
|
Control the Injection Volume for A/F Sensor |
|
Data List Display |
|---|
|
Coolant Temp |
|
AFS Voltage B1S1 |
|
O2S B1S2 |
(f) Change the fuel injection volume using the Techstream, and monitor the output voltage of the air fuel ratio sensor (AFS Voltage B1S1) and heated oxygen sensor (O2S B1S2) displayed on the Techstream.
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 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:
|
Techstream Display (Sensor) |
Injection Volume |
Status |
Voltage |
|---|---|---|---|
|
AFS Voltage B1S1 (Air fuel ratio) |
12.5% |
Rich |
Below 3.1 V |
|
-12.5% |
Lean |
Higher than 3.4 V |
|
|
O2S B1S2 (Heated oxygen) |
12.5% |
Rich |
Higher than 0.55 V |
|
-12.5% |
Lean |
Below 0.4 V |
|
Status AFS Voltage B1S1 |
Status O2S 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 |
|
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 |
|
C |
|
Lean/Rich |
Rich |
Heated oxygen sensor malfunction |
|
|
|
Lean |
Lean |
Actual air fuel ratio lean |
|
D |
|
Rich |
Rich |
Actual air fuel ratio rich |
|
- Lean: While performing the Active Test "Control the Injection Volume for A/F Sensor", 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: While performing the Active Test "Control the Injection Volume for A/F Sensor", the air fuel ratio sensor output voltage (AFS Voltage B1S1) is consistently below 3.1 V, and the heated oxygen sensor output voltage (O2S B1S2) is consistently higher than 0.55 V.
- Lean/Rich: While performing the Active Test "Control the Injection Volume for A/F Sensor", the output voltage of the fuel ratio sensor (AFS Voltage B1S1) or heated oxygen sensor (O2S B1S2) alternates correctly.
HINT:
Refer to "Data List / Active Test" [AFS Voltage B1S1 and O2S B1S2].
Click here
| B |
|
| C |
|
| D |
|
|
|
3. |
CHECK FOR EXHAUST GAS LEAK |
(a) Check for exhaust gas leaks.
OK:
No gas leaks in exhaust system.
| OK |
|
| NG |
|
|
4. |
REPLACE AIR FUEL RATIO SENSOR |
(a) Replace the air fuel ratio sensor.
Click here
HINT:
Perform "Inspection After Repair" after replacing the air fuel ratio sensor.
Click here
| NEXT |
|
|
5. |
CHECK FOR EXHAUST GAS LEAK |
(a) Check for exhaust gas leaks.
OK:
No gas leaks in exhaust system.
| NG |
|
|
|
6. |
REPLACE HEATED OXYGEN SENSOR |
(a) Replace the heated oxygen sensor.
Click here
HINT:
Perform "Inspection After Repair" after replacing the heated oxygen sensor.
Click here
| NEXT |
|
|
7. |
CHECK FOR EXHAUST GAS LEAK |
(a) Check for exhaust gas leaks.
OK:
No gas leaks in exhaust system.
| NG |
|
|
|
8. |
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 the DTC P0171 and P0172 Inspection Procedure.
Click here
| NEXT |
|
|
9. |
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.
Click here
|
|
10. |
CLEAR DTC |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Clear the DTCs.
Powertrain > Engine and ECT > Clear DTCs
(e) Turn the ignition switch off and wait for at least 30 seconds.
|
|
11. |
CHECK WHETHER DTC OUTPUT RECURS (DTC P0420) |
(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(b) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(c) Read the DTCs.
Powertrain > Engine and ECT > Trouble Codes
|
Result |
Proceed to |
|---|---|
|
DTCs are not output |
A |
|
DTC P0420 is output |
B |
| A |
|
END |
|
|
12. |
REPLACE FRONT EXHAUST PIPE ASSEMBLY (TWC: FRONT AND REAR CATALYST) |
NOTICE:
When replacing the front exhaust pipe assembly in order to replace the three-way catalytic converter, it is not necessary to replace the heated oxygen sensor.
HINT:
Confirm the replacement parts, referring to the illustration in the Catalyst Location.
(a) Replace the front exhaust pipe assembly (TWC: Front and rear catalyst).
Click here
| NEXT |
|
END |
|
|