When does catalytic convertor need replacement? Check engine light periodic/

Likely it is your converter that is failing assuming you have a P0420 catalyst efficiency code. It is always recommended to have the operation of the oxygen sensors checked before replacing the catalyst but more times than not the catalytic converter is at fault. When a converter becomes plugged you will experience a loss of power and replacement is necessary, however if its just inefficient you can drive without any issues until it comes to needing an emissions test. We use factory converters which are very expensive but I never have installation or operation problems with these. If you purchase an aftermarket converter expect it to last 1-3 years. You also want to check the drivability of the vehicle making sure the plugs/wires and other ignition components are operating properly. If there is a driveability problem you need to address that first and foremost. Good Luck--A

Hello, They need replacement when they stop filtering out harmful chemicals from the exhaust, which is noticed by the oxygen sensors. When you get an oxygen sensor fault, the three options you noted are the basic three, but doing nothing will destroy your fuel mileage. If the engine has efficiency issues, you will get emissions codes as well.