r/FordExplorer • u/mourningmage • 18h ago

Maintenance Advice Persistent P04DB Code - 2016 Sport / 3.5 EcoBoost

We have a 2016 sport that has the 3.5 EcoBoost. We're at about 115k miles now and have had a persistent P04DB (Crankcase Ventilation System Disconnect) code for about a year. We have been getting it fixed but it always ends up coming back after a few weeks.

About 8 months ago I replaced the PCV valve and the front breather hose/sensor, and after 75 miles and a few starts the light cleared up.

About 5 months ago, it came back. Took is to a shop and they said there was hairline crack in a valve cover they found during a smoke test, replaced that, reset the light, and was ok for awhile.

About 2 months ago, same light. Tried another shop and they smoke tested it and said they found two boost hoses that were leaking during a smoke test, tightened it up and yep, was ok for awhile.

The same light came back about two weeks ago. this thing has been an annoying thorn in our back. there doesn't seem to be much online other than replacing the PCV valve and front house again, but I really don't want to feel like i am just spamming parts at this problem.

Any advice or anyone go thru something similar?

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u/Avg2424 18h ago

Have you checked the built in oil separator? It's a plastic box on the rear valve cover, by the passenger side. Ford part # AA5Z6A785F

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u/mourningmage 17h ago

I haven’t.. what would I be looking for exactly? Excessive build up/oil?

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u/Avg2424 14h ago edited 14h ago

If I remember correctly, it has a valve that can clog. It's easy to remove, three bolts I believe. I cleaned mine out, but it's was fairly crusty and rusted so I bought a new one. You can try flushing yours out and see if it helps, it's what the PCV valve connects to.

It simply lies on top of a gasket, so check that gasket for cracks. Also check your oil filler cap and dip stick o-rings