2003 Mazda 6 2.3L FI The pcv valve is located behind the intake manifold, with some patience and small hands you can get to it. First unplug your negative battery cable, You must remove the 8 bolts holding the intake to the engine, there are several vacuum hoses and sensors that must be unplugged, the oil tube must be unbolted, there is a hole in the middle of the intake with a bolt in it, tough to get to but it can be done with patience, there is also a bolt you will have to get to from under the vehicle. I removed the throttle body for easier removal and to go ahead and clean it. Removal is always harder then installation as you get familiar with the procedure. If you need help i can do a step by step, i just finished fabricating a new hose for a pcv and reinstalling it. You can not get the molded hose from an auto parts store, i used 2 90 degree elbows and 3 pieces of hose, this makes the hose more durable with less span between connections and less chance of another crack in it.