I have a 2010 a4. It is putting up a "lean at idle" code. If I get it above 4500 rpm the EPC light comes on. I turn the car off and back on and it goes away. At idle there is vacuum coming from a small hole on the crankcase pressure regulating valve. Is that my problem?

 

Bad crankcase valves usually affect idle conditions. try pulling the oil cap off with the engine running , if it is difficult to pull off the valve is bad.

 

I've had this issue as well except I had that system too lean CEL/code permanently. If there is a oil residue around the oil cap area and too much suction (engine about to stall when you remove) then valve is probably going bad.

I changed the PCV valve, PCV hose. Also this cured the oil burn problem as well.

 

I had the oil burning problem. The dealership had to install new pistons 3 time. Had my car for almost 2 month. And in those 2 months I went through 3 loaner cars. The first 2 had oil consumption problems if you could believe that. They did get mine fixed and it is doing very well. I haven't had to add any oil in almost 12 months and 30,000 miles! Anyway, thanks for the advise. I will try the oil cap when I get home today.

 

Ok, it almost took two hands to pull off the oil cap. I guess that means it's bad. Where is the best place to get one? If I have to buy something I always like to upgrade, is there an upgraded valve? Thanks...

 

Installed a new CPR valve today. I have reset the check engine light and drove it about 30 miles. The check engine light did not come back on. The EPC light still comes on if I go over 4000 rpm and it goes into safe mode. Any ideas on why this is? When the EPC light comes on it does not throw any codes...