If your CEL light comes on and you hear a lumpy idle. Got to Autozone and find you have code P0171.
This is a well known problem.. its almost certainly the PCV valve that has failed.
To confirm remove the snap on cover on top of the engine with "Ecotec" written on it. Underneath you will see a round thing on the top right hand of the valve cover directly in line with the oil filler.
There is a small hole on the top.. if there is air being sucked IN through the hole the PCV valve has failed (the diaphram has a split in it).
This is covered under the power train warranty but the dealer will want an $85 diagnosis fee.. complete stinking rip off.
Sadly the whole valve cover has to be replaced but you can buy a genuine GM valve cover on line for $53 shipped to your door and will take about 20 minutes to swap.
I do have a modification I am working on which means you can fix the problem for about $5.. then replace with aftermarket PCV valves for $2 in the future.
So if you have a Cruze and suddenly this issue comes up.. Please write to me before you spend like $300 at the dealer if yours is out of warranty.
Frank
