P0420
DTC P0420 / P0430NOTE: For identification of each cylinder and bank, refer to Precaution for Identification of Cylinder and Bank.
Wiring Diagram:
System Description
ECM calculates the oxygen storage capacity of TWC and monitors the ability of TWC to convert the exhaust emission effectively. ECM calculates the oxygen storage capacity under specified driving conditions as follows.
1. ECM commands the fuel injection status to rich (air/fuel ratio: low) until all oxygen is released from the TWC.
2. ECM commands the fuel injection status to lean (air/fuel ratio: high) until any one of the following conditions is met, and ECM calculates the oxygen storage capacity of TWC by MAF sensor output signal and duration.
- Saturation of oxygen in the TWC is detected by output signal of HO2S-2.
- Before the saturation of oxygen is detected, the lean status of the fuel injection is longer than specified time. (ECM judges that the oxygen storage is higher than specified value.)
DTC Confirmation Procedure
WARNING:
- When performing a road test, select a place where there is no traffic or possibility of a traffic accident and be very careful during testing to avoid occurrence of an accident.
- Road test should be carried out by 2 persons, a driver and a tester, on a level road.
NOTE:
- If DTC other than aimed DTC are previously detected in DTC confirmation procedure, be sure to troubleshoot DTC previously detected.
- Make sure that the following conditions are satisfied when using this procedure.
- 0.7 V < Battery voltage < 18.1 V
- Ambient temperature > -30 °C (22 °F)
- ECM calculates the average of oxygen storage capacity based on the last 6 measurements.
- ECM calculates the oxygen storage capacity up to 3 times per 1 driving cycle.
- The past measurements of the oxygen storage capacity are deleted when the DTC is cleared or the battery is disconnected.
- In case that the past measurements of oxygen storage capacity are deleted, it is necessary to perform the DTC confirmation procedure at least 2 driving cycles in order to complete the diagnosing of oxygen storage capacity.
1. Clear DTC.
2. Start engine and warm up to normal operating temperature.
3. Drive vehicle at 60 - 80 km/h (37 - 50 mile/h) for 10 min. (Keep throttle valve opening constant and engine speed 2,500 rpm or less in this step.)
4. Turn ignition switch to OFF position for 1 min.
5. Repeat step 1) through 3) if past measurements are deleted.
6. Check whether catalyst readiness / monitoring test has completed using scan tool. If readiness / monitoring test has been incomplete, check vehicle conditions (environmental) and repeat Step 3) through 4).
DTC Troubleshooting
