P0401 EGR Flow insufficient fault

I have a 2003 jetta wagon that is getting the P0401 EGR fault. I have stored the fault data from the car for the last 4 faults. I can reset the fault and it will not come back for 3-4 days.

Calc Load % 31.37 31.37 31.37 28.63
ECT degF 161 129 163 156
MAP inHg 35.14 33.66 36.03 35.44
Eng RPM 1722 1698 1768 1722
Veh Speed 46 35 47 25
Spark Adv 3 4 2 3
IAT degF 32 39 25 35
MAF lb/min 4.06 4.06 4.06 4.06
TPS % 26.67 25.1 27.06 0.0

It seems strange that the MAF is always the same number, could I have a MAF sensor problem? I looked at the EGR valve and it has no build up on it. Also I can move the EGR valve easily with the lever. The fault always comes on near 1700 rpm, is the engine expecting to move the EGR at that time?

I changed the MAF sensor. I seem to have more power but I get the same fault. I have also noticed that coolant temperature has a hard time staying on the middle mark. When I am driving around the city it never quite makes it to full temperature and will drift down after I am on the highway. I there a common part that controls the EGR and coolant temperature?

Look through some of my recent posts regarding the p0401 code. You will find the problem I was experiencing and what I did. Also PUTER has an excellent writeup which I found very helpful.

I disconnected the vacuum line at tee number 10. I connected a mightvac and it would not hold the vacuum. The tee connector and line was clear.

I check the vacuum pressure with the car running. It went to the maximum of the mity vac guage. I also disconnected the vacuum line to the EGR and moved it with the mightvac. The egr is dirty but it moves. I am not sure if it opens completely. It stops moving at 20 lbs of pressure.

The EGR cooler pipes can get plugged up, as can the intake manifold. I'd check both. You can clean the cooler out with the EGR pipes removed. Use a coat hanger wire and rod out the tubes inside the cooler. You can get to most of them. Blow the crap out with compressed air or Dust Off. The cooler can stay mounted on the car with coolant hoses attached. Be careful, you do not want to puncture the cooler.

--Nate