overheating car on 1998 Honda Civic

why does my car overheat after replacing catalytic converter

Asked by for the 1998 Honda Civic
I have seen the catalytic converters fail and the exhaust manifolds crack but the over heating issue is not due to having replaced the catalytic converter,
The most likely causes of over heating could be a coolant leak, a stuck closed thermostat, an electric fan not operating or a blown head gasket.