I have a 2007 Chevy Equinox about 104K mi. A couple weeks ago the check engine light came on and now it intermittently keeps stating Service Stabilitrak and Service Traction Control. Pull the codes and comes up with P0404, P0405, and P0171. I've seen some reports of the same thing and they said they replaced the EGR valve and it worked great. I replaced my EGR valve and the lights all went off for about a day. Another post I read said their may be a loose vacuum line. I can't find any. Does anyone have any advice?? I don't want to just replace parts at random. Thanks.

It could be that the passage that the egr valve is in, is plugged with carbon.

I looked at the passage valve too. Looks like the EGR is working good. Now the only code that comes up is p0171, fuel too lean. Saw a lot of posts about cleaning mass air flow sensor or having a loose vacuum line. Checked all that and cleaned mass air flow. Even added some fuel system cleaner. Light was off for a bit, but the engine light came back on. Also, the service stabiltrak indicator came back on too.

On our 07 equinox we occasionally get the P0171 and it has always been the fresh air pcv tube that runs from the air cleaner to the valve cover on the firewall side of the engine. When my wife was taking it to get oil changes they would man handle the air filter box and snap the tube off the valve cover. Sometimes it has been able to just be put back in other times it has needed replaced. I found it on Gmpartsdirect.com and the part number is 12602539. by that tube being off the engine will pull fresh air through it that is not metered by the mass air sensor and then on the radiator side of the engine there is the return air tube that connects to the intake manifold there fore bringing in air that is not metered by the mass air flow sensor.

Thanks, but that tube is tight on both ends and no signs of holes or cracks. Still stumped....

Is something low on oil and exposing a sensor

Thanks a bunch. I replaced both o2 sensors and the pcv tubing only to find this tubing loose at the engine side.....damm....it was my own doing too. I had just recharged the k&n......I must have knocked out loose then. ..

I have EXACTLY the same two problems: "Service Stabilitrak" and am engine code for the EGR. 2007 Pontiac Torrent (your twin). Replaced the EGR and the light was off for a day but has come back on...twice. Sorry, no solution/answer from me.

I had the same issue. Like the guy above said...find the vacuum line that goes from the MAF (or off the back - the engine side of the air filter cover box) from the passenger side toward the driver side. Follow that line all the way to the end - and it should be connected on the firewall side of the engine. This iin particularly common if you've had a recent oil change or some other service at a shop. They often disconnect it by accident and never notice it is disconnected. They're ignorant of how easily that comes out, or even that there is one there.

I found the same problem with my 2007 Eqiunox. Am seeing codes P404, P405, and P2138. The crankcase ventilation tube is broken off at the valve cover. There is still a bit of the push in plastic fitting stuck in the valve cover. Any suggestions on how to get it out of there?

I got the broken piece of plastic out of the valve cover using an old 3/8" tap.

I have had the same problem and after a year of guessing I finally un clogged the egr passage and runs better than new