EGR problems - P0401

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Mar 11, 2007 | 07:48 PM

ssanto

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EGR problems - P0401

Hi,

I have a P0401 EGR code on my 1997 F-150 with a 4.6 L V8. I pulled the EGR to clean it out and it wasn't clogged at all. It opened just fine when I applied a vacuum to it. When I put it back on the truck I checked the functionality by sucking a vacuum on it at idle and the engine stumbled when the EGR opened.

So I figured the DPFE sensor was going out. I removed it and its ports were very clogged up. I got a new one but the P0401 error didn't go away.

The EGR has a vacuum line going into it that is coming from what looks like a solenoid to connect or disconnect the EGR from vacuum. The "in" side of the solenoid is a vacuum line that runs across the engine to the passenger side and back under the firewall.

At idle, the "in" side of the solenoid does not have any vacuum on it. So I don't see how the EGR could ever work if the vacuum that is supposed to operate it isn't there.

Should the line going into the solenoid that connects the vacuum to the EGR always have vacuum?

Any suggestions?

Thanks,
Sal

Mar 11, 2007 | 08:08 PM

12swat

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From: Michigan

Take the throttle body off and all hoses/linkage etc. Then take the piece that connects your throttle body to the intake off. The ports to the egr valve on this piece will most likely be clogged shut with carbon gunk. The only way to get to them is to pull this piece off. I just took mine off and cleaned it on my 97 4.6L. My code (p0401) has been clear for a couple of weeks. Run a search on the P0401 code and there will be further details on removing this piece and cleaning it. It is not that hard. I bought replacement gaskets before disassembly in case I tore a gasket.

Mar 12, 2007 | 06:48 AM

projectSHO89

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From: St Louis

The vacuum line to the EGR valve comes from the EVR solenoid. The solenoid should only open to apply vacuum while at steady-state cruise, never at idle or during acceleration. The supply side of the EVR solenoid (white hose) should have vacuum applied to it at all timesthat manifold vacuum is present to the inlet of the large vacuum reservoir (inside fender).

Steve

Last edited by projectSHO89; Mar 12, 2007 at 06:51 AM.

Mar 12, 2007 | 07:20 AM

ssanto

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Hi Steve,

Just to make sure... the EGR solenoid is the thing on the drivers side kind of near the DPFE sensor. It has a white vacuum line going into it and a green one coming out of it (that goes to the EGR). It has an electrical connector on it.

The white line going into it has no vacuum... so that is probably the problem. Even when the solenoid opens no vaccum will ever find the EGR.

Thanks,
Sal

Mar 12, 2007 | 07:46 AM

projectSHO89

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From: St Louis

Quote:

Originally Posted by ssanto

Yep, you got it.

Find the loss of vacuum on that white hose. On my 97, it goes back to a larger coupler located between the battery and the firewall. Also, on my 97, a second white hose is in the same bundle that goes ftom that same coupler to the fuel pressure regulator. You might want to check it also to see if vacuum is getting to it.

Steve