Check engine light code says bank one is running lean, what can i do

SOURCE: check engine light on

Check out this site as it tells you exactly the problem http://www.obd-codes.com/p0171
Hope this helps

SOURCE: bank 1 burning to lean check engine light on flunked state emissions

It is a common problem, you will have to change bank 1, o2 sensor as it is covered in burnt oil and fuel telling the computer to run lean.
hope this help

SOURCE: CHECK ENGINE LIGHT CAME ON P0171 FUEL TRIM BANK1 SYSTEM TO LEAN.

Hi. You need to clean the Mass Air Flow Sensor.
This is an easy job.
Get a can of throttle body or brake cleaner spray at your local auto parts store.

Open the hood, and locate the air filter box. follow the tube from the filter box towards the engine. Look for a small black box with 2 screws holding it to the air tube, Remove the wire connector and observe inside the sensor with a flashlight. You will see 2 small wires, and they will appear fuzzy or dirty. Spray the interior with the cleaner until the wires are nice and clean. Do not use compressed air, you will damage the sensor. Put it all back together and drive it.
This will def fix your issue. This is a vey common problem. If you do it yourself, you will save 70 + bucks.

Thanks for choosing FixYa, and a FIxYa rating for my assistance would be greatly appreciated.

SOURCE: the code of p0171 ,how to fix

You can try cleaning the MAF first:
http://www.fordf150.net/howto/clean-maf-mass-airflow-sensor.php

If the code comes back after clearing it, check the spark plugs (not an easy task). My 2000 Expedition had fouled plugs....the 5.4 has a bad head design with recessed spark plugs.

SOURCE: have this code PO171, what does this mean.

Not sure that the O2 sensor was bad. It sounds like it was telling you that side of the exhaust system was picking up a lean mixure at the O2 sensor. The O2 sensor was doing its job by telling you the mixture changed. If the O2 sensor was bad, it would say low voltage range for that sensor, or open curcuit.
Now the car has had time to do its diagnostic sweep, it is telling you the same thing, but from a different sensor...the fuel mix is too lean. Air/spark/and fuel is what you need in the correct amounts. In your car, the ECM engine control module controls this by taking readings from all the sensors several hundred times a second.
Mechanically, you have a few options. Change the fuel filter...under the car on the passenger side. It is an easy job.
Change the fuel pressure regulator. This keeps the fuel at 4 BAR so the fuel injectors can do their job correctly. This job just needs a screw driver to pop off the clip that holds it in place. No hoses need to be removed. It is on top of the intake manifold, in-line with a metal fuel line and a rubber one.
The fuel injectors could be clogged up on one side of the engine. Run some fuel injector cleaner through a tank of gas. Also, listen for a constant ticking sound at each injector. If one sounds off PAR, then replace it.
The fuel pump may not be giving you enough power. However, the readings seem to be localized to one side, so I doubt it.
Start with the easiest thing, and see if it works. Also, you will need to get yourself a VAG scan tool. It is the only one with codes in it for all of your VW systems, not just engine codes like the ODB scanners. You can get a nice one for $50 on-line.
Good Luck!