Hello everyone, my new A4 is idling rough, I pulled CEL code and it was P0171.
I searched and found that this code is due to bad maf or PCV. My question is how do I know which one is bad? I am at 59k.

 

anyone?

 

With this engine's history with PCV valves, it's most likely the PCV valve. When my Jetta's MAF sensor went bad, the car ran normal most of the time, with just an emissiions workshop warning message, and would occasionally go into mass convolsions, that would end when you restarted the engine. The PCV valve on this engine has been revised multiple times.

 

thank you, I am going to replace the PCV, the hose and gasket