How do you replace the exhaust manifold on a 1999 Honda Civic LX?

Ill assume that yours cracked.

You have to purchase a replacement manifold with a catalytic converter bolted up to it. It is usually a one piece set up. It costs about $300 after market or about $500 OEM from Honda.

To replace it:

-Remove the primary o2 sensor with a 22mm socket

-Remove the secondary o2 sensor at the end of the catalytic converter

-Remove the 12mm bolts that connect the manifold to the head

-Remove the 14mm bolts with spring that connect the down pipe to the exhaust

-Wiggle it out through the bottom or the top

-Reinstall the new one using these steps but in reverse.