Code P0420 indicates that the Bank 1 Catalyst System efficiency was below threshold for a predetermined period of time.
This condition will prevent the vehicle from running at its optimum efficiency and fuel economy may suffer.
Sensors indicate the catalytic converter is not reducing exhaust gas emissions properly.
OSC value smaller than standard value under active air-fuel ratio control (2 trip detection logic)
Possible Causes:
Front exhaust pipe Gas leakage from exhaust system
Air-Fuel Ratio (A/F) sensor (sensor 1)
Heated Oxygen (HO2) sensor (sensor 2)
