2001 Ford Expedition, Testing The EGR Valve

This 2001 Ford Expedition came in and the customer requested that the EGR valve be changed. I asked why and was told the parts store checked it and it had a code P0401 for insufficient EGR flow. I said okay, but I was willing to bet  that the EGR valve was okay. The customer asked why I was so sure and I informed him that I have repaired a code P0401 in many different Ford vehicles, hundreds of times and I have never changed an EGR valve to fix this code. I am not saying that the EGR valves cannot fail but I personally have not seen it be the cause of an insufficient egr flow code. I told him it would take about five minutes to test the valve. First I went and got my hand vacuum pump, as pictured below.

I located the ERG valve on the driver’s side of the engine.

I disconnected the vacuum hose.

With the engine idling I hooked up my hand vacuum pump and applied about 25″ of vacuum to the EGR valve.  The engine idle surged down almost to a stall condition and then recovered and ran a little rough. The valve held vacuum and the engine almost stalled so the valve is good and the passages are open. We need to look for something else and not waste money on replacing a good EGR valve.

If the valve would not have held vacuum the valve would have been faulty. If it would have held a vacuum and the idle speed changed very little or not at all, the valve would most likely have been okay and the egr passages would have been blocked with carbon build up. Another thing to keep in mind is that if no change in engine rpm is noted, the engine should be turned off and then apply vacuum to the EGR valve again. Movement of the pintle and the diaphragm should be heard and felt, while applying vacuum and during quick release of the applied vacuum. . If vacuum is held and no movement is detected the EGR valve itself may be stuck. The customer paid the bill and said he would be back but I have not seen him yet. This one or another one will come in soon and I will document what really is the problem.

5 discussions on “2001 Ford Expedition, Testing The EGR Valve”

  1. This is a followup to my previous comment on the EGR valve that I found stuck. I replaced the original EGR valve with a new one, and the P0401 code went away & did not return over the next 11 months. I did nothing to the vacuum relay, so apparently it was not part of the problem.

  2. Thank you for your comment. I went back and added a little more information to the end of the post to detect if the EGR valve may be stuck as it was in your case. Since your EGR valve was stuck you may want to consider that the vacuum relay may not be working the EGR valve and that it was stuck due to non movement for an extended time.

  3. This is an old post, but an issue that comes up time and again. I’ve had a P0401 – insufficient EGR flow – on my 2001 F150 4.2L. I actually ran the test Sparky suggested on my EGR right after I bought my handheld vacuum pump from Harbor Freight. Sure enough, the engine stumbled & almost died. At the time I did this, the F150 was much newer. Later it threw a P0401 code. I repeated the vacuum pump test with the same equipment on the same vehicle – nothing happened. I removed the EGR valve – it was full of black gunk. Lots of carb cleaner & scraping later, I could see the valve stem. When I applied vacuum, nothing at all moved inside the EGR. I applied max vacuum – still nothing. I left the vacuum connected (gauge read about 30 psi) and set the whole assembly down. A minute or two later, something “popped” really loud. Re-inspection showed the EGR was now open. Releasing & reapplying vacuum now showed the EGR valve moving. Whether it moves correctly enough to solve my P0401 problem remains to be seen. I think the chemical & manual cleaning I did was critical to making the EGR valve open – this could not have been done without removing it. But I will install a new EGR valve anyway, rather than fuss with this 11 year old valve any more.
    The EGR valve is easy to remove and replace on my model.

  4. I have been informed that I need a new EGR valve for an insufficient egr flow code by my local parts store. Can I check the valve at home without a vacuum pump? What should I check next?

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