Might want to double check all your hose and electrical connections. It really sounds like there is a leak somewhere. I wouldn't bother disconnecting the battery anymore, the CEL will keep coming back as long as the fault condition is still there. When you get it fixed, the light will go out and stay out. CEL basically indicates that engine does not seem to be operating within normal bounds and is probably polluting more than it should. If a sensor is unhooked or a hose is leaking, you'll get the symptoms you describe.
