My civic is not passing smog because it's failing at idle only but all the rest passed. So what can be the issue assuming if it wasn't the the head gasket that is leaking?

 

What is failing? CO or HC? Miles on the engine? Engine type?

 

It's a 92 cx motor an it has about 230000 miles on it but last month one of the small water line that connects to the head to the intake manifold was leaking or might have poped and my car was over heating on the freeway to work. I had a three more miles left so I kept driving it until I got to work.

 

You still didn't answer what you failed for. HC or CO ?

If you over heated your engine and drove it that long then most likely you warped your head and head gasket is leaking coolant into the combustion chambers causing a misfire OR low compression situation. If that's the case. Then you'll need to replace the Head gasket and check the head for warpage.