Q: Check Engine light says replace catalytic converter

It would be helpful to know the exact code in this case. The Check Engine Light themselves do not tell us to replace components, they point us to a possible cause of a malfunction. If the code is for catalytic efficiency, which would cause a flashing Check Engine Light, the vehicle should not be driven. A failed catalytic converter can cause engine damage if continued driving. A qualified technician, such as one from YourMechanic will be able to confirm the cause Check Engine Light and perform an exhaust flow test if needed. They will also be able to replace the catalytic converter if this is verified to be faulty.