The check engine code P0171 means System Too Lean (Bank 1), according to Obd-Codes.com. This means that the oxygen sensor in bank 1 detected a lean condition, or too much oxygen in the exhaust.
It is unlikely that drivers will notice any issues with the car, however symptoms such as lack of power, rough idle, or hesitation on acceleration may appear. Typical causes of this include low fuel pressure due to a faulty fuel filter, the Mass Air Flow (MAF) Sensor is dirty or the oxygen sensor itself may be faulty. Solutions are as simple as cleaning the MAF sensor or as challenging as changing out the fuel filter.