O2 simulators on the downstream O2 sensors will take care of that as a cheaper and easier solution. If the car is stock and keeping it stock is preferred the converters will need to be replaced. The computer monitors the converters through the oxygen sensors. When the downstream O2's start switching as fast as the upstream O2's the computer fires the check engine light. The Bank1 and Bank2 refers to the side of the motor, Bank1 being the passenger side (all fords), cylinders 1-4 and Bank2 being drivers side cylinders 5-8