97 F-150 "MIL" problem

My brother's 97 F-150 XL 4.6L SOHC V8 (5 spd) just threw a check engine code on him. So I went out and plugged my Xcal2 in and read the engine code:

P0401 -- EGR FLOW, INS DET

I dont know what the "INS DET" meant, but i'm clearly guessing he has an EGR problem. Can anyone get back to me on what this code is for or what the problem is?

When I went out to the car and turned it on, the check engine light was not on, but my brother said it came on while he was driving it. Truck has 80,000 miles on it i think (if memory serves).

From doing a tune up on his car early in the summer, i discovered he has a passenger side leaking valve cover gasket that we never got around to fixing...but i dont think this has anything to do with the EGR problem, but thought i'd share the info anyway.

svttech76 said:

The most common cause of the problem is the DPFE sensor. second most common is a clogged EGR passage. To test if the passage is clogged get a vacumm pump and pull some vacumm on it at idle it should stall if it does not then the passage is clogged or the valve is bad. But I would put the odds in the 90 percent range that it's the dpfe or one of the hoses going to it.

Click to expand...

Hmm thanks mike, i'll give it a shot and get back to you guys this weekend.

And what is a DPFE sensor? Should i just look into replacing it....?