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Check-engine code P0456

Tiny
AMMARSALMAN94
  • MEMBER
  • 2006 MERCURY MILAN
  • 2.3L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 173,000 MILES
A few months ago I hit a pothole and the check-engine light immediately came out. The exhaust fell and I put it up again.

Anyway, while driving later on, I made a hard stop (pushed the brakes strongly) and the gas cap light came out (I know it sounds crazy but I swear this is what happened). Then, I changed the gas cap and erased the codes from the car. I drove about two hundred miles on it and the check engine light came back.

I then ran the car, opened the oil-cap and noticed lots of blow by coming out from there. I was told it is a bad sign, I have also checked with a friend to see his vehicle and nothing was blowing out of the oil-cap. By the way, I changed the oil today.

I know the mileage is high on my car, but the blow-by is really big.

I was told that the PCV valve might need a change, so I bought a new one and when I wanted to replace it, I had no idea where to locate it -.-

So my questions are:
1. Is the high blow by a sign that my engine is about to die?
2. If the blow-by is not related to the check-engine code (P0456) then what is and how can I fix it?
3. Is it safe to drive the car for long rides (six hundred miles going and coming back)?
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Wednesday, May 24th, 2017 AT 6:47 PM

3 Replies

Tiny
JIS001
  • MECHANIC
  • 3,408 POSTS
P0456 is for a very small evap leak. That will not cause any drivability problems and all that means your vehicle is releasing small amounts of raw fuel vapors into the atmosphere. You would need to have the evap system checked for leaks. Most of the time it will be a leaking purge valve but proper diagnosis needs to be done to verify the problem.

As for the PCV blow by, that will not really cause any drivability issues also but it can cause seals to blow and create an oil leak if it is plugged up. Every vehicle is different with the pcy system. European vehicles you will feel a slight vacuum when you place your hand over the oil fill hole. Sometimes the pcv system will have an internal leak and make a squealing or honking noise?

To start with I would recommend you replace the oil separator. That box is the heart of the pcv system. You will need to remove the intake manifold to access it. Once there you can actually replace the valve and I recommend you replace the hose. See the picture I posted.

Hope this info helps and lets us know if you did the repairs.
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Wednesday, May 24th, 2017 AT 10:32 PM
Tiny
AMMARSALMAN94
  • MEMBER
  • 8 POSTS
After doing smoking test on the evap system I found out that the Vent Solenoid Valve was broken. Ordering and replacing it did the trick. The codes faded away as the valve was replaced.
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Sunday, December 31st, 2017 AT 3:32 PM
Tiny
JIS001
  • MECHANIC
  • 3,408 POSTS
Thank you for the update and posting the fix.
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Sunday, December 31st, 2017 AT 5:46 PM

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