Help With EGR!!

Ok, every few months it seems like, my check engine light pops up a P0401 - EGR flow insufficient. I took it in and they replaced the EGR twice in a two month period an also replaced a few hoses (if memory serves...). I'm really curious as to why this thing goes away, but then comes back so sparsely? Anyone have any suggestions/ideas??? :sly:

The PCM module uses engine vacuum via the MAP sensor to test EGR flow when the test is called upon during a drive cycle. So check all the vacuum lines at the MAP sensor and back to the throttle body and supercharger. The MAP sensor can be tested to see if the output is correct. Also, a bad PCV valve can cause the EGR flow test to fail. Which includes missing any seals like the PCV o-ring.

Correct me if I am wrong, but would not that code also pop up if the gas cap were not sealing correctly too?

Not to my knowledge. The gas cap codes are the P0440 series DTCs. See link below.

Click here (http://www.automotiveforums.com/vbulletin/showthread.php?t=622473)

Not to my knowledge. The gas cap codes are the P0440 series DTCs. See link below.

Click here (http://www.automotiveforums.com/vbulletin/showthread.php?t=622473)

Crap, you're right, my bad. Im sorry about that. Guess Im not doing too good on diagnostics.

I agree with Bob that it's most likely a vacuum issue. It's rare that this code is indicating an actual problem with the EGR valve itself. Re-check the lower black o-ring on the PCV valve to be sure it's still there and intact.