Question

P0420 2001 Toyota Highlander - I already replace new cat converter, bank 2 sensor 1, bank 2 sensor 2, bank 1 sensor 1, and still get the error code P0420, need help?

Answer 1

P0420 Catalytic below threshold Bank 1

Use a scan tool to read what Bank 1 Sensor 2 threshold is at. if the 02 voltage is below 0.650 volts you need another catalytic convertor. You also should not have any exhaust leak just prior to the front 02 sensor. or exhaust leak prior to the catalytic convertor