P0420
DTC P0420: Catalyst System Efficiency below ThresholdWiring Diagram:
System / Wiring Diagram
Circuit Description
ECM monitors oxygen concentration in the exhaust gas which has passed the three way catalytic converter by HO2S-2.
When the catalyst is functioning properly, the variation cycle of HO2S-2 output voltage (oxygen concentration) is slower than that of HO2S-1 output voltage because of the amount of oxygen in the exhaust gas which has been stored in warm up three way catalytic converter and three way catalytic converter.
DTC Detecting Condition and Trouble Area
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: Check to make sure that the following conditions are satisfied when using this "DTC Confirmation Procedure".
- Intake air temp.: Between -10 degrees C and 70 degrees C (14 degrees F and 158 degrees F)
1. Connect scan tool to DLC with ignition switch turned OFF.
2. Turn ON ignition switch and clear DTC using scan tool.
3. Increase vehicle speed to 50 - 60 mph, 80 - 100 km/h. (engine speed: 2500 - 3000 r/min.)
4. Keep the vehicle speed for 10 min. or more (Throttle valve opening is kept constant in this step).
5. Stop vehicle and check if DTC / pending DTC exists using scan tool. If not, check if catalyst monitoring test has completed using scan tool. If not in both of the checks (i.e., no DTC / pending DTC and catalyst monitoring test not completed), check vehicle condition (environmental) and repeat step 3 through 5.
Step 1 - 3:
DTC Troubleshooting