1997 Honda Civic failed smog check in California

Exhaust manifolds are extremely hard to weld. Ive had this same problem on this vehicle before where it cracked in between the 2 ports. Exhaust manifolds are made from cast iron and are a lot harder and thicker than the rest of the exhaust. The manifold is probably the second hottest part of the entire exhaust system and is always rapidly cooling and heating up which causes the metal to expand and contract which would completely destroy a weld. So my advice, is to replace the manifold. You can weld it for now as a bandaid to pass inspection but it will crack again where the weld is.