Where is PCV valve located on Mazda 6?

The pcv valve is located behind the intake manifold, with some patience and small hands you can get to it. 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 bolted, 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. You can remove 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.

that's the new PCV valve...which end is the side with the threads? ("Left" or "Right" will suffice)

Here is the only input you need, the PCV valve is a crappy design, they haven't quite owned up to it yet. The crappily designed PCV valve shoots oil from the cam cover into the intake manifold, to which is burned off with the gas/air mixture inside the cylinders and then expelled in a blueish tinge of smoke out the exhaust pipes in some cases.In some cases nothing is noticed from exhaust pipes.--------

the pcv hose on a Mazda 6

it is located underneath the inlet manifold
It actually depends on whether you are talking about Mazda 6i (4 cylinder engine) or 6s (6 cylinder). I own 6i and it is located under the intake manifold and you can't reach unless you remove the manifold first. For 6s the PCV hose is behind the engine close to the firewall.
Correction: You can change the pcv hose on a 2.3L without removing the manifold. You can get to it from underneath and it connects at bottom back of manifold and at the top. Look through the space on right of manifold in front top and you will see it. You''ll need lighting and flashlight possibly to see it as it is in a hard to get place. The ends of the hose are offset 90 degrees. Unbolt the starter and move out of your way. I also took off the throttle body and hose, the two shuttle valves also. Then you can stand in front and reach underneath to attach the top part of the hose on the nipple. The nipple is made out of nylon so don't break it, after its on work your clamp into place. I had to take the insulating cover off and clamp the top first then put the cover back on. You''ll have to lay underneath to clamp the bottom connection. I jacked the front side up and used a stand as added safety. Just jack it enough to get under. The top connection is a hassle and you may need to pry it with a large screwdriver just don't break the nipple. Lube the hose and nipple first. The old hose had a 2 inch slit/crack in it. It caused the car to idle rough/stall and shift hard from 1st to 2nd. After replacing hose the car runs great. It has 80k on it. Bad engineering to replace a $15 hose that is so critical to the emission system. This job is for shadetree mechanics that like to do this stuff and have some knowledge of auto mechanics etc.

the pcv valve is located on the valve cover on the rear bank (closest to the firewall) on the throttle body side.

if you look just behind the intake manifold you'll see a black plastic tube sticking up out of the valve cover.

that is you PCV valve.

Check both pcv valve and also the hose, to which the valve line is connected.The valve needs to be replaced, but if hose looks cracked then replace the hose too.

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