Ok I have replaced the DPFE sensor about 3 months ago and the EGR valve last week. I have been about 250 miles since the new valve and my check engine light has come on again for Insufficient EGR Flow again. I will tighten down the bolts holding the valve on and the pipe going in to the valve but much past that I am at a lost. Anyone have any ideas? The guy at AutoZone said that I may have a leak somewhere else in the system. Does this sound right? If so, how would I go about determining where a leak is coming from?

Truck Info:
2001 F150 xcab
4.6L V8
2wd
78k miles

 

I found a leak in an EGR hose running Sea Foam through. As the Sea Foam was being sucked in, I noticed the smoke leaking out the hose. I hadn't been throwing any codes or had any other signs that I had a hose leak, but it made it pretty obvious and easy to find.

I've heard other people say to spray carb cleaner or something similar around the hoses. If you have a leak, you'll notice a change in the engine idle.

 

Had this happen and it turned out the intake manifold port was plugged. Cleaned out the port and the error code went away.
Roger

 

I second that. It is very common for the EGR ports in the upper intake plenum to become clogged. The best way to clean is remove the TB, remove the EGR and the vacuum lines then remove the upper intake. First manually clean the holes then soak the whole intake in carb cleaner for a while and blow them out. I have done this several times to my truck. Now when I have the plenum off I just go ahead and clean the ports.

 

Thanks folks for the reply's

I ended up taking it to a shop at lunch. Believe it or not the guy actually has said the same thing, which to me is not normal for a mechanic to say all it needs is to be cleaned more then likely and not well you need about $500 worth of parts. He said if you have already replaced the sensor and valve that the next thing would be to clean the intake, which his cost is going to be about $80. I figured that is not to bad, considering I have already spent more then that in parts for the sensor and valve. I had been looking at the nice write up that was done on how to clean the intake and decided that was a little more then I wanted to try and tackle. Mainly because I don't know of a weekend I will have free to be able to do it for the next month or so.

I think the first thing related to the EGR system should be to clean the intake and then see if the light comes back on before changing out the sensor and valves, seems like I might have seen that before when I was reading some threads on this problem. Knowing my luck that was all that was needed. Oh well guess you live and learn, and if I come out under $200 total (sensor+valve+clean) I'll be happy.

 

i changed all that stuff too and my light stayed coming on. Then I was told it is my throttle body ports for the egr valve so I just finshed taking it of and cleaning it. I was plugged solid. I couldn't believe how hard the build up was and how much because I only have 89,000 miles on it. It is a easy job, cheaper than buying all those parts for nothing. Took me about 35 min You might want to try this

 

Whenever I see code P0401, I clean the ports and replace the DPFE & EGR valve. Don't sweat changing out the parts. Just call it preventative maintenance. Now your EGR system will be good to go for at least another 60K miles.

 

Well as luck would have it the light came back on yeserday when I was driving home, after the shop had cleaned the throttle body. So I took it back in this morning. They cleared the code then the guy and I drive around for about 10mins or so while he monitored the system with a more advanced scan tool then the ones that just read the codes. He noticed that the EGR sensor never changed it's reading but the scan tool was showing the valve was opening. So it sounds like I have a clogg some where going to the sensor. I guess the cleaning of the throttle body did not include anything past that. Anyway this was at least the first concrete data on the problem. I doubt that the sensor is bad because, it's only 3 months old and if it was the sensor it would have tripped the code that the sensor was bad and not the insufficient EGR flow.

 

Ok now things get really weird. My shop is not going to be able to get to my truck until this Tuesday (also having the high pressure power steering hose replaced) to look for the clog in the EGR system. Today at lunch when I started the truck the check engine light went off! I shut off the engine and turned it to the on position (not turned over) to make sure the light was still working and it was. My original problem looks to be a clog somewhere due to the fact that the DPFE sensor never changed it's reading when it was monitored while driving, obviously this will be the first thing I ask the shop to check tomorrow.

So if it was a clog and say it has now worked it's way lose, would the code get reset after it has enough good readings? I thought that you either had to have the code cleared with a scan tool or disconnect the battery to clear the code. Also if it was in fact a clog of some sort that is now free, is there a need to worry?

I have only been about 2miles at lunch so the real test will be to see if it can last 10-15miles which seems to be the range that trips the code for Insufficient EGR Flow.

 

i dont have egr anymore...so i have massive inssuficient flow but no code thrown or anything like that :-P