Mazda6 2.3L Running Poorly

So the Mazda6 started running poorly and the check engine light came on the other day.  Code P0171 Lean Bank 1.  Adriane said the engine acted like it wanted to die and idled terriblely rough and sometimes would be very hard to stop the car by standing on the brakes.  Since it had 90,000 miles on it I thought we need to get a tune up going.  Not much to tune up on this car…  4 new platinum spark plugs and a wire set, new air filter and clean the Intake Air sensor along with the MAF sensor.  I even cleaned the tar off the throttle body.  Start her up and she still idles rough…  This car has a known exhaust leak issue so it was tough to hear the vacuum leak over the exhaust but you could certainly hear it.  It was coming from underneath the plastic intake manifold.  I went and ordered the intake set to replace the rubber gaskets it uses for the intake and got online to see how hard it was going to be to take apart.  In the forums I saw several posts about how the PCV valve is located directly under the intake manifold and is NOT reachable without removing the intake.  Apparently the PCV valve hose develops a large tear or split after the first bend.  This was most likely the source of the vacuum leak.  Online everyone said it was like  $500 to $600 job to replace the hose.  I ordered the hose and valve from Mazda and waited until they came in before tearing into the removal of the manifold.  It wasnt too bad of a job but really terrible that you need to remove the intake manifold to get to a PCV hose.


  1. Hi Adam,
    Thanks for helping us to locate the PCV valve of the breather hose.
    Would you be able to tell me where the other end of the hose goes.
    I would not like to take off the manifold and follow the hose.
    I would be grateful.

    • Wojtek-

      The hose connects to the intake manifold which you can see on img_1318 on the lower left corner of the intake manifold. Good Luck.


  2. eljefebusa says

    Thank for the input i have the manual and i ddnt find any like this thx so much

  3. Mike Gordon says

    do you have to take off the fuel rail and injectors?

  4. Hi Adam,

    Thanks for those pics. Would you be able to tell me if you had to remove the power steering to get far left bolt off?


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