I got a code today. some help please.

[Bdirt]

p0171 left bank lean. I just had all the coils plugs and valve cover gaskets replaced about 11 to 13,000 mi ago. Do you think I just need to replace my 02 sensors? That was the only code it was giving. It is a 01 v8 non sport.
prob rare that it came on when at 122,222mi ,wish I got a pic of that.

 

[CobraStar_LS8]

switch o2 sensor from the other side and reset code and then you wait til code comes up and if it says right bank instead then it's the o2

 

[LS4me]

Gingerly shoot some carb/choke cleaner on the MAF. I got that code plus a P0174. I ordered the rear O2 sensors, but don't need them yet. I will be replacing the MAF as the stocker has ~168K miles on it.