P0420
2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0420,P0430: Catalyst System Efficiency Below Threshold (Bank 1)
DTC P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
DTC P0430 - Catalyst System Efficiency Below Threshold (Bank 2)
MONITOR DESCRIPTION
The ECM uses the sensors mounted in front of and behind the three-way catalyst converter to monitor its efficiency. The first sensor, an air fuel ratio sensor, sends pre-catalyst air fuel ratio information to the ECM. The second sensor, a heated oxygen sensor (O2S), sends post-catalyst information to the ECM. The ECM compares these 2 signals to judge the efficiency of the catalyst and the catalyst's ability to store oxygen. During normal operation, the three-way catalyst converter stores and releases oxygen as needed. The capacity to store oxygen results in a low variation in the post-three-way catalyst converter exhaust stream.
If the catalyst is functioning normally, the waveform of the heated oxygen sensor slowly switches between RICH and LEAN. If the catalyst is deteriorated, the waveform will alternate frequently between RICH and LEAN. As the catalyst efficiency degrades, its ability to store oxygen is reduced and the catalyst output becomes more variable. When running the monitor, the ECM compares sensor 1 signals (air fuel ratio sensor) over a specific amount of time to determine catalyst efficiency. The ECM begins by calculating the signal length for both sensors (for the rear oxygen sensor, the ECM uses the output voltage signal length). If the oxygen sensor output voltage signal length is greater than the threshold (threshold is calculated based on the air fuel ratio sensor signal length), the ECM concludes that the catalyst is malfunctioning. The ECM will turn on the MIL and a DTC will be set.
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.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
MONITOR RESULT
Refer to CHECKING MONITOR STATUS Mode 6 Data.
CONDITIONING FOR SENSOR TESTING
HINT: Perform the operation with the engine speeds and 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 the appropriate inspection results.
1. Connect the Techstream to the DLC3.
2. Start the engine and warm it up with all the accessories switched off, until the engine coolant temperature stabilizes (Procedure "B").
3. Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes (Procedure "C").
4. While running the engine at 3000 rpm for 2 seconds and at 2000 rpm for 2 seconds, check the waveforms of the air fuel ratio and heated oxygen sensors using the tester (Procedure "D").
HINT:
- If either of the voltage outputs of the Control the Injection Volume for A/F Sensor does not fluctuate, or either of the sensors makes a noise, 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 following using the Techstream.
- If the three-way catalyst converter has deteriorated, the heated oxygen sensor (located behind the three-way catalyst converter) voltage output fluctuates up and down frequently, even under normal driving conditions (active air fuel ratio control is not performed).
1. AIR FUEL RATIO CONTROL
Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F Sensor function provided in the Active Test. The Control the Injection Volume for A/F Sensor function can help to determine whether the air fuel ratio sensor, heated oxygen sensor and other potential trouble areas are malfunctioning. The following instructions describe how to conduct the Control the Injection Volume for A/F Sensor operation using the Techstream.
(a) Connect the Techstream to the DLC3.
(b) Start the engine and turn the tester on.
(c) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(d) Select the following menu items: 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 in an idling condition (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 tester.
HINT:
- The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Standard voltage:
CAUTION: 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, select the following menu items on the tester: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS Voltage B1 S1 or AFS Voltage B2 S1 and O2S B1 S2 or O2S B2 S2. Then press the graph button on the Data List view.
INSPECTION PROCEDURE
HINT: 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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
PROCEDURE
1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420 AND/OR P0430)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch on (IG) and turn the tester on.
(c) Select the following menu items: 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
A -- Continue to next step.
2. PERFORM ACTIVE TEST USING TECHSTREAM (AIR FUEL RATIO CONTROL)
(a) Connect the Techstream to the DLC3.
(b) Start the engine and turn the tester on.
(c) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(d) Select the following menu items: 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 in an idling condition (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 tester.
HINT:
- The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Standard voltage:
Result:
Lean: During Control the Injection Volume for A/F Sensor, the air fuel ratio sensor output voltage (AFS) is consistently more than 3.5 V, and the heated oxygen sensor output voltage (O2S) is consistently less than 0.4 V.
Rich: During Control the Injection Volume for A/F Sensor, the AFS is consistently less than 3.1 V, and the O2S is consistently more than 0.55 V.
Lean/Rich: During Control the Injection Volume for A/F Sensor of the Active Test, the output voltage of the heated oxygen sensor alternates correctly.
C -- CHECK AND REPLACE HEATED OXYGEN SENSOR, AND CHECK AND REPAIR EXHAUST GAS LEAKAGE
B -- REPLACE AIR FUEL RATIO SENSOR
A -- Continue to next step.
3. INSPECT FOR EXHAUST GAS LEAK
(a) 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 the ON position and turn the tester on.
(c) Enter the following menus: Powertrain / Engine and ECT / Trouble Code.
(d) Read the DTCs.
Result:
B -- REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH
A -- Continue to next step.
5. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY RH
(a) Replace exhaust manifold sub-assembly RH Removal
NEXT -- REPLACE CENTER EXHAUST PIPE ASSEMBLY
6. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH
(a) Replace exhaust manifold sub-assembly LH Removal
NEXT -- REPLACE CENTER EXHAUST PIPE ASSEMBLY