P0420

DTC P0420

DTC Detecting Condition and Trouble Area






Circuit Diagram

Circuit Diagram:

System Description
ECM monitors oxygen concentration in the exhaust gas which has passed the TWC by HO2S. When the TWC 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:
- Perform road test in a place where there is no traffic to prevent an accident.
- Road test should be performed by two persons, a driver and a tester, on a level road.

NOTE:
- Be sure to troubleshoot first unexpected DTCs previously detected in "DTC Confirmation Procedure".
- Confirm that the following conditions are met in this "DTC Confirmation Procedure".
- ECT >= 70 °C (158 °F)
- DTC P0131, P0132, P0137, P0138 or P2237 is not detected.

1. Warm up engine to normal operating temperature.
2. Drive vehicle at 50 - 100 km/h (31 - 62 mile/h) for 10 min. (Keep throttle valve opening constantly and engine speed at 1,400 - 3,500 rpm in this step.)

DTC Troubleshooting

Step 1-8: