Hi, I have a 1999 Ford F150 XLT 4.6 V8 truck and my check engine light came on 2 days ago and has stayed on. I took my truck to Auto Zone to have it checked out and I was told that my ECM has detected too little flow on the EGR system. It gave me a P0401 code and I open the hood and took the vacuum holes off and there was very little air suction coming from the line so I figured it was stopped up somehow. I know I might need to change the EGR out, but is there any way to tell why the line suction is weak to no existence. I have also been in several floods here in Houston Texas and the water was pretty high but never had the truck to stall, it just made a high pitch noise... sound like it was coming from underneath the rear?

 

Welcome to the site..

First,, whats the model/engine/year? other than truck

You won't see a high constant vacuum at the EGR port.. The vacuum is routed to a solenoid and the PCM is in command of the solenoid for a release.. Most have a DPFE sensor that is used as an input to measure/regulate the flow.. They tend to fail from heat, moisture and corrosion..

 

Thanks for your help.....
I was also told that I might need to do something like a carbon flush...what ever that means before replacing the EGR or any other part because if there is a build up of carbon or the valve have carbon on it so to speak....the flush would clean it up. I hope I explained that correctly. By the way where is the DPFE located on the F150?

 

What year 150, and what engine?

 

Hi, I have a 1999 Ford F150 XLT 4.6 V8 truck and my check engine light came on 2 days ago and has stayed on. I took my truck to Auto Zone to have it checked out and I was told that my ECM has detected too little flow on the EGR system. It gave me a P0401 code and I open the hood and took the vacuum holes off and there was very little air suction coming from the line so I figured it was stopped up somehow. I know I might need to change the EGR out, but is there any way to tell why the line suction is weak to no existence. I have also been in several floods here in Houston Texas and the water was pretty high but never had the truck to stall, it just made a high pitch noise... sound like it was coming from underneath the rear?

 

The DPFE is a box looking unit sitting right in front of the EGR valve.. It has 2 larger silcone hoses attaced that run down to a tubing manifold.. It has a single electrical connector on its face..

They do have a very high failure rate, but not always the cause for the low flow code. If you can run a small secondary vacuum hose off of the EGR valve tap/port and 'physically' apply enough vacuum (or use a vacuum pump) the engine should idle very rough or stall..

Another option..

In front of the DPFE is the EGR Vacuum Regulator (EVR solenoid) its a black plastic piece with a round cap on top.. It has 2 vacuum hoses at its base in a rubber connector unit.. When unplugged idling, one side or 'circuit' of the rubber plug should have a constant steady vacuum (the supply) and the other side or circuit routes over to the EGR valve for a vacuum application when commanded by PCM and the solenoid opens the valve (EVR) operating the EGR valve..

As a test of the EGR, use a small piece of tubing or ? and with the engine idling carefully unplug the connector so not to over bend the plastic tubing portion and connect the 2 rubber ports together, or run a single add on vacuum line/hose to the EGR vacuum port from the rubber connector (vacuum side).. The vacuum will instantly open the EGR and the engine should stumble or stall..

If it does stall, I'd suspect the DPFE, or a blockage in the DPFE manifold for setting the code.. Most cases its the DPFE itself.

If it doesn't have a large affect on the idle, then I'd look at the EGR and/or a restriction..

 

Thanks I will see if I can follow what you said and try to correct the problem or find someone who can....

 

Oh another thing what do you think would make the engine tick, sometimes loud or sometimes for a few minutes it runs with no ticking...I don't know if it's the lifters or what but the sound comes from the right hand side of the engine toward the front of the motor.

 

Almost same problem except I get a PO406. I found moisture in the ref leg of the DPFE and my truck almost cuts off at idle. Any suggestions?
Thanks

 

i have a 02 f150 with a v-6 and my check engine light keeps coming on this is a list of things replaced fuel pump egr 4 cats o2 sensors both sides maf sensor plugs wires fuel filter pcv valve keeps saying running rich on right bank at my wits end