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That is an image of a Subaru EJ253 with a white component off of the upper air intake plenum. The component in question has a red box digitally drawn around it.

What is that component?

Here's a significantly larger image.

Thank you.

  • An electrically controlled valve, but lack of detail means can’t say more , try getting closer so we can see where it goes to ...
    – Solar Mike
    Mar 22 '18 at 20:15
  • i.imgur.com/jmCuaYw.jpg
    – NitrusInc
    Mar 22 '18 at 20:28
  • I think it's the solenoid for the PCV.
    – Ben
    Mar 22 '18 at 20:33
  • Agree with @Ben here. The hose looks like it goes down to the valve cover. Mar 22 '18 at 20:35
  • 1
    @Pᴀᴜʟsᴛᴇʀ2 It definitely does route to the PCV valve. I just don't remember if it's a sensor or solenoid. Can't seem to find it in service info.
    – Ben
    Mar 22 '18 at 20:52

It the PCV Diagnosis Connector (E51). It routes to D12 on the ECU, and the other side is grounded.

It's a sensor of sorts, not a solenoid or valve. It's really nothing but a mechanical "switch" that shorts when the hose is connected. If you disconnect the hose, it opens and causes the ECU to generate a proprietary Subaru P1xxx DTC:


You can monitor it in ROMRAIDER. It's always "1" or "ON" ... unless you disconnect the hose. It tells absolutely nothing about the PCV valve function, pressure, flow, leaks, or if the other end of the hose is disconnected.

It's really rather silly I suppose. Nothing to worry about unless you're putting in a Perrin turbo kit or something that deletes the stock PCV system. In that case you simply short the two wires in the connector, or permanently ground D12 at the ECU. Or disable P1491 with ROMRAIDER. (All off-road use, of course...)

  • Ah, i thought that was it, but mitchell doesn’t reference it on non turbo applications so i wasn’t sure. They don’t even show it in the non turbo wiring diagram
    – Ben
    Mar 24 '18 at 5:49

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