I own a 2007 Lacrosse that I purchased last June with 36K . A few weeks ago the CKL came on. I hooked up my scanner, and it threw code P0401. I pulled the EGR, checked everything and sprayed it full of WD 40. After letting it sit for a couple of hours, I blew it out an reinstalled it. It was fine for about 2 weeks, the the light came on again, P0401. I went through the cleaning process again, same results. The engine runs fine. I am thinking that my only option is to replace the EGR, even though there is no guarantee that will fix the problem. Any suggestions?

 

Look very carefully and thoroughly at the intake manifold itself where the EGR mounts . Look for any burned through areas.

 

So far, I have replaced the EGR, checked mounting for cracks, removed the the EGR intake hose and checked that, removed and checked the PCV valve. When I clear the code, it will return in about 2 days. During this whole time, the engine runs great and never stumbles.