I've got an 01 A4

I just had my A/c recharged and the K&N filter cleaned out(i dont think it dried enough) and it threw this code-P0171 system too lean( bank1).

There was a vacuum leak but i fixed that. i erased the code and drove for 50 miles A/c off(i drive windows down). I thought the problem was solved. As soon as my mom drove it she put on the A/c and soon thereafter(like 30 seconds) code popped up.

So i cleaned out the MAF, erased the code and test drove( a/c off). everything was fine. then my mom drove it- A/c on, code popped up.


There isnt a vacuum leak. The MAF is still original- Could the MAF be bad or for whatever reason the A/C be involved or that was just coincidence? How about the O2 sensor? And this all happened the day before i was going to get the car inspected...Any help would be awesome!!