2000 Civic Exhaust Gasket Crack
 

I have had this 2000 Honda Civic LX 189K miles for about a month. Gradually going through it, while cleaning up the engine, I took off the heat shield covering the exhaust manifold right of the Head. Found a crack on the top towards a sensor screw in port, I believe it is a 02 sensor. See photos Below.
Some background info, It was just registered and passed the smog last month.
I have seen some other threads about this same problem so I assume it is fairly common. My first question is what is the urgency to do something about it.
Second, it is possible and or advisable to attempt a patch type fix, I am familiar with JB weld, or maybe something specifically made to tolerate high heat. Is there any harm in trying something like that first, and any specific recommendations on how to do it.
Finally if I do need to replace it, I know that the Cat Converter is separate from the Ex Manifold or do they both need to be replaced?
Or any other words of advice for this situation?
Thanks in advance for your attention and or recommendations
Bob

https://drive.google.com/file/d/1sHo...ew?usp=sharing
https://drive.google.com/file/d/1DHb...ew?usp=sharing

Re: 2000 Civic Exhaust Gasket Crack
 

If it's an LX the cat is integrated to manifold. If it passes smog I'd just keep it covered with the heat shield and call it a day. If the noise is bugging you though then it's better to replace it, repairs don't really hold up. The cheap ones are cheap for a reason, try to go for a more expensive one that is legal for wherever you are