Its been 477 days since you posted this question now and I am still finding more old questions on this site but I will still answer them.
Yes in certain states it is required that your car passes the Emissions test. Driving down the highway will heat up the exhaust comming out and as they said, flush out any buld up in the engines Postive Crankcase Vetilation or PCV system.
The catalytic converter is one of the things to go first on an older car. To prevent pollution of the atmosphere from incompletely burned and evaporating gases, and to maintain good driveability and fuel economy, a number of emission control systems are incorporated. They include the Self diagnosis system, Eletronic engine controls, Feedback Control systems, Exhaust Gas Recirculation or EGR system, Secondary air supply or air injection system, Fuel evaporative control system, Positive Crankcase Ventilation or PCV system, Intake air temperature control sysytem, and the Catalytic converyer. Remember, the most frequent cause of emissions problems is simply a loose or broken vacuum hose or wire, so always check the hose and wiring connections first. There should be a Vehicle Emissions Control information or VEC label that is attached to the underside of the hood. This label contains important emissions specifications and adjustment information. There should also be a second label, called the Vacuum Hose Routing Diagram, this provides a vacuum hose schematic with emissions components identified. Now if you get a repair manual for your car it will show you how the emissions control system realy works. Yes I could put a picture here for you but it will be copyrighted. I would have to draw it out myself just to show you. The manual will cost you around $12. In the mean while check everthing that I wrote down first. Then when your ready to replace something get the repair manual. You can pick it up at your local auto parts store. Now I'll explain how the catalytic converter works. The catalytic converter is an emission control device added to the exhaust system to reduce pollutants from the exhaust gas stream. Theres two types of these converters. The conventional oxidation catalyst reduces the levels of hydrocarbon or HC and carbon monoxide or CO. And theres the three way catalyst that lowers the levels of oxides of nitrogen or NOx as well as hydrocarbons and carbon monoxide. You can tell if the catalytic converter goes bad by taking it off and then by moving it around. The catalyst inside will rattle or move around inside. If it doesn't then it could be burnt out to a point where it doesn't do the job like it should and that is turning the HC and CO into CO2. Which is alot safer to the environment. So even though this question was posted over 477 days ago I hope you solved the emission problem. Now if a car is just five years old and fails the test. They recommend that the car should have more miles on it in order to be passed by the emissions test or insted of putting alot of miles on it just replace the items that I stated earlier and then it should pass the emissions test. If you have any more questions on this topic let me know and I will give you a detailed answer.
This answer was edited by Electrical 35 days ago.
Reason: Added
