Newbie here. Great site. Did not know that Terrain has forum until now . Anyway I brought my 2010 Terrain 4 Cyl AWD to the dealer to fix the code (check stabilitrac... sp) and also to check on rough idling and noise when idling a few weeks ago. They changed the solenoid but did not find the other complained that my wife experienced and said that the solenoid does a lot of weird things too. Work and drive okay until 2 days ago. Now the lights came ON. Went to Advance to read it and it is PO172 (too rich). I also hearing some noise on the engine while it is on idle. My milage just reach over 36,400 miles. Is this something on the power train warranty? Is anyone having similar problem? Was the fix under warranty? I love this GMC as with my 2001 Yukon XL and this truck went to the dealer more than my Yukon that has over 105k mile (never went in for service). Car is driven by my daughter and my wife. Any info is greatly appreciated.