What does code 442 mean

Hello, I assume you mean that the code is P0442. This is a code related to a fault detected in the evaporative emissions system. It means the system has detected a small leak. This leak could be from something as simple as a fuel filling cap that is not securely tightened. It could definitely be more complicated, considering the fuel filler neck, the canister purge valve and system components, and other relevant evaporative emissions system components. One thing to be sure: it is not at all related to replacing the head gaskets in and of themselves. Check to make sure all hoses and fittings are properly secure under the hood, as obviously things were disconnected and removed to access those head gaskets. Other than that, a proper diagnosis, including possibly using as smoke vapor machine to detect a small evaporative emissions system leak will be required to see what's going on. Good luck! For some help near you, click this link to find some qualified techs! http://repairpal.com/jeep-within-10-miles-of-bowie-texas-76230