[fyrffytr1]

My sister-in-laws 2000 Ford Explorer with the 4.0 engine is showing a PO401 code when hooked to the OBD scanner. The scanner also has two icons flashing, one says cat and the other eva.
The 401 code reads as a generic exhaust gas recycling problem. The truck idles rough but smooths out when given gas. We changed the EGR valve and a solenoid that is hooked to the valve by a vacuum line.
Could it be one or more of the catalytic converters or something else? If it was an older (pre-computer) car I would say it had a weak spark plug or a vacuum leak but I am lost when it comes to computer cars.
Thanks for any and all help.

[Bill Eveland]

Most egr issues are the DPFE , it's aluminum or plastic housing with 2 vacuum lines going to it bolted to the driver side of the intake manifold. Does that sound like what you replaced? 9J460 is the base part #.

[fyrffytr1]

That sounds like it.It has an electrical connector as well. There are two vacuum lines running from the bottom of it.
When I took the vacuum line off the EGR valve it did not affect the engine. But, when I hooked it back up the engine would almost die for just a second then catch back up.

[Bill Eveland]

There is also an EGR vacuum regulator that controls vacuum to the egr . Those go bad as well. Unless thats what you replaced, you'll still need the dpfe.

[fyrffytr1]

Bill,
Is that the same thing as the idle air control valve? That is what was causing the problem. She got it fixed today.

[Bill Eveland]

Idle air control valve is on it's own.