A good article covering diagnosing the problem with P0172 - http://www.gmtruckhq.com/diagnostic-...-2-a-3933.html

 

hey guys thanks for all the input, i am not sure how to test my cat and fuel system pressure but i might bring it in some where and have the cat and fuel system checked, i am a guy who always does his own stuff but i am stumped and do not no how or have the equipment that can test those systems. i just saw this post on a buick regal forum with someone that has the 2.4. I think i might invest in a new fuel pump.

Sorry for the delay on the update. Here's what we found out.
The Code that was stored was P0172. Basically, The high pressure fuel pump failed, and contaminated the crank case. They replaced the fuel pump, and changed the oil. This is a known problem from what I understand, and it was covered under the powertrain warranty. From what the shop told me, the fuel pump's circumference bores out, and puts out too much pressure to the point that fuel passes through into the oil.
Hope this helps out other Regal owners out there.
Also, the same problem is know to happen with the following:
2011 Regal
2010-2011 LaCrosse
2010-2011 Equinox
2010-2011 GMC Terrain
all with the 2.4L engine (RPO LAF)