Lean Condition on e46

[toymachine595]

Hey guys,
I'm normally in the e21 and e36 forums but I know a guy that is having a problem and was wondering if I could ask you guys a question.
The car is a 2001 325i, I'm assuming its the m54 motor. Anyways apparently the car is throwing a code number P0171 and P0174 which I checked on ALLDATA and they are Bank 1/Bank 2 System too lean. I haven't seen the car myself and I can't get over to him to take a look, so I figured maybe someone had a similar problem here and had an idea. He said it doesn't appear to have an obvious vacuum leak. The guy has mechanical experience so I would say anything obvious has been checked over so If anyone has any experience with a similar thing let me know what you think.
Thanks.
-Kyle

[Numark318i]

I believe those are codes for the Throtle position sensor. P0174 is atleast...i believe.

[marti5]

I would go for the MAF sensor.