Do you have to get a no sensor if gut your catalytic converter?

No, you don't have to get a 02 sensor if you gut your catalytic converter. Gutting a catalytic converter is illegal in most states and can cause your vehicle to fail emissions testing. An 02 sensor is used to monitor the oxygen content of the exhaust gases and adjusts the fuel mixture accordingly. Without a catalytic converter, the 02 sensor will read incorrectly and the vehicle will run poorly.