You have the same EGR valve I do. The little 'mushroom' digital EGR. I'm assuming you don't have a scantool, so you'll have to do it a bit simpler. These usually suffer from a mechanical binding. There'* 3 spring-returned solonoids in that sucker.
When mine threw the last code in June, I simply went in there with WD-40 and sprayed the shafts. Use this as a SOVENT, not a lube. It dissipates too quickly. Also use it to clean out the electrical connector, both sides, and let it drip out.
If this solves the problem, use a hi-temp LIGHT grease or teflon based lube on the shafts for long-term lube.
If this doesn't work, you need to check the solonoids with an ohmmeter. The pinout goes like this:
Imagine the triangle where the harness plugs in as being an arrow to the RIGHT, ie: the longer point goes to the right. Pin A is on the far right, B is in the center, C is top left, and D is bottom left.
a-d should be 20-30 ohms
b-d should be 20-30 ohms
c-d should be 10-17 ohms
If any of these are incorrect, you're replacing the valve.