P0420
1GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0420, P0430: Catalyst System Efficiency Below Threshold (Bank 1)
P0430 - Catalyst System Efficiency Below Threshold (Bank 2)
MONITOR DESCRIPTION
The ECM uses sensors mounted in front of and behind the front catalyst 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 (OSC) 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 OSC 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 rich-lean cycle of the heated oxygen sensor is long, the OSC becomes greater. There is a direct correlation between the OSCs of the heated oxygen sensor and three-way catalytic converter.
The ECM uses the OSC value to determine the state of the three-way catalytic converter. If any deterioration has occurred, it illuminates the MIL and stores the DTC.
HINT
* Bank 1 refers to the bank that includes cylinder No. 1.
* Bank 2 refers to the bank that does not include cylinder No. 1.
* Sensor 1 refers to the sensor closest to the engine assembly.
* Sensor 2 refers to the sensor farthest away from the engine assembly.
CATALYST LOCATION
Text in Illustration
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
MONITOR RESULT
Refer to Checking Monitor Status Mode 6 Data.
CONFIRMATION DRIVING PATTERN
HINT
Performing this confirmation driving pattern will activate the catalyst monitor. This is very useful for verifying the completion of a repair.
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC operation).
5. Turn the ignition switch off and wait for at least 30 seconds.
6. Turn the ignition switch to ON and turn the Techstream on [A].
7. Enter the following menus: Powertrain / Engine and ECT / Monitor.
8. Check that Catalyst / Status2 is Incomplete.
9. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [A].
10. Drive the vehicle at a speed between 64 and 113 km/h (40 and 70 mph) for 10 minutes or more [B].
HINT
The monitor items will change to Complete as the catalyst monitor operates.
11. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
12. Check if any DTCs (pending DTCs) are stored.
HINT
If Catalyst does not change to Complete, and no pending DTCs are stored, extend the driving time.
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 in order to activate the sensors sufficiently to obtain appropriate inspection results.
1. Connect the Techstream to the DLC3 (a).
2. Start the engine and warm it up with all the accessories switched off until the engine coolant temperature stabilizes (b).
3. Run the engine at an engine speed between 2500 rpm and 3000 rpm for at least 3 minutes (c).
4. 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 Techstream (d).
HINT
* If the voltage output of the air fuel ratio sensor or heated oxygen sensor does not fluctuate, or there is noise in the waveform of either sensor, the sensor which has those problems may be malfunctioning.
* If the voltage outputs of both 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 has deteriorated, the heated oxygen sensor (located behind the three-way catalytic converter) voltage output fluctuates up and down frequently, even under normal driving conditions (active air-fuel ratio control is not performed).
INSPECTION PROCEDURE
HINT
* Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. 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.
* Bank 1 refers to the bank that includes the No. 1 cylinder*.
*: The No. 1 cylinder is the cylinder which is farthest from the transmission.
* Bank 2 refers to the bank that does not include the No. 1 cylinder.
PROCEDURE
1. CHECK FOR ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420 OR P0430)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine and ECT / Trouble Code.
(d) Read the DTCs.
Result
HINT
If any DTCs other than P0420 or P0430 are output, troubleshoot those DTCs first.
B -- GO TO DTC CHART SFI System
A -- Continue to next step.
2. PERFORM ACTIVE TEST USING TECHSTREAM (A/F CONTROL)
(a) Connect the Techstream to the DLC3.
(b) Start the engine and turn the Techstream on.
(c) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
(e) Perform the Control the Injection Volume for A/F Sensor operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
(f) Monitor the voltage outputs of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2, or AFS Voltage B2S1 and O2S B2S2) displayed on the Techstream.
Standard:
Air fuel ratio sensor reacts in accordance with increases and decreases in fuel injection volume:
+25% = Rich output
Below 3.1 V
-12.5% = Lean output
Higher than 3.4 V
NOTICE:
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.
Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / AFS Voltage B1S1 or AFS Voltage B2S1 and O2S B1S2 or O2S B2S2. Then press the graph button on the Data List display.
Result
D -- CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR-FUEL RATIO, REPLACE FAULTY COMPONENTS AND GO TO NEXT STEP
C -- CHECK FOR EXHAUST GAS LEAKAGE
B -- REPLACE AIR FUEL RATIO SENSOR Removal
A -- Continue to next step.
3. CHECK FOR EXHAUST GAS LEAKAGE
OK:
No gas leakage.
NG -- REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK -- Continue to next step.
4. CHECK DTC OUTPUT (DTC P0420 AND/OR P0430)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON and turn the Techstream on.
(c) Enter the following menus: Powertrain / Engine and ECT / Trouble Code.
(d) Read the DTCs.
Result
D -- REPLACE FRONT NO. 2 EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST AND REAR CATALYST) Removal
C -- REPLACE FRONT EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST AND REAR CATALYST) Removal
B -- REPLACE FRONT NO. 2 EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST AND REAR CATALYST) Removal
A -- REPLACE FRONT EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST AND REAR CATALYST) Removal
5. CHECK FOR EXHAUST GAS LEAKAGE
OK:
No gas leakage.
NG -- REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
OK -- REPLACE HEATED OXYGEN SENSOR Removal