DPFE Failure?
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Joined: Oct 2001
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From: Muncie
DPFE Failure?
Hello,I have read the many posts concerning code PO401,followed the tests as outlined,many times,to be sure I was getting it correct.I have also cleaned the E.G.R. passages,valve.replaced hoses and the tube going to the exhaust.My problem is that I still get the PO401 code about every four to six months.When this happens,voltage at th DPFE is 4.9V D.C.,instead of the max. of less than 2.0V D.C.(I think the spec.is .2 to1.9) I replace the DPFE,clear the code,problem solved for another four to six months,then same thing again.I have purchased my sensors at the discounters(Autozone etc.) as well as at Napa,Carquest,and Ford. Any help will be greatly appreciated. Thank You . Oh Yeah,I forgot,I have a 99 F150 4x4 5.4 L.
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Joined: Sep 2006
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It may be the EVR causing the repeat 401 failure.
Why; the routine calls for the EVR to allow the EGR to flow at a certain rate.
The DPFE checks if that flow is within limits.
If not the code is set. Doesn't make a difference what part fails, it is still detected as the same failure.
The EVP may be marginal in allowing the correct flow. It has an air filter within it's body that allows clean air into the EGR once it is opened and may be sluggish in operation. Check the vacuum lines to the EVR and EGR for faults.
The 401 test must fail two times in succession to be considered a failure.
You may also be getting a lot of water vapor causing carbon to accumulate since the exhaust is not very clean.
Use only Ford OEM replacements.
Hope you have better luck. There's not much more to be a cause.
Why; the routine calls for the EVR to allow the EGR to flow at a certain rate.
The DPFE checks if that flow is within limits.
If not the code is set. Doesn't make a difference what part fails, it is still detected as the same failure.
The EVP may be marginal in allowing the correct flow. It has an air filter within it's body that allows clean air into the EGR once it is opened and may be sluggish in operation. Check the vacuum lines to the EVR and EGR for faults.
The 401 test must fail two times in succession to be considered a failure.
You may also be getting a lot of water vapor causing carbon to accumulate since the exhaust is not very clean.
Use only Ford OEM replacements.
Hope you have better luck. There's not much more to be a cause.
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