P0420

DTC P0420

DTC Detecting Condition and Trouble Area

Wiring Diagram

Wiring Diagram:

System Description
ECM monitors oxygen concentration in the exhaust gas which has passed the TWC by HO2S. When the catalyst is functioning properly, the variation cycle of HO2S output voltage (oxygen concentration) is slower than that of A/F sensor output signal because the amount of oxygen in the exhaust gas is stored in TWC.

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 with 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.
- Check that the following condition is satisfied when using this procedure.
- ECT > 70 °C (158 °F)

1. Warm up engine to normal operating temperature.
2. Drive vehicle at 80 - 100 km/h (50 - 62 mile/h) for 10 min. (Keep throttle valve opening constantly and engine speed at 2,500 - 3,000 rpm in this step.)

DTC Troubleshooting

Step 1-8: