Buick runs lean p0171

SOURCE: my 97 buick stalls some time and wont start for while

code po 171 system lean on bank one on 2002 buick lasabre

SOURCE: P0171 Code (Lean Fuel Bank 1) Engine light on

PO 171 indicates a lean condition in bank 1 or the same side of the engine as the first cylinder , usually it is caused by a vacuum leak some where check to make sure that even the smallest of vacuum hoses are in good condition and not leaking

SOURCE: 96 Buick Roadmaster running lean.

That is an oxygen sensor, these sensors send a signal to the computor to adjust the rich/lean fuel mixture.
When a code comes up for them, they generally need replacing.

SOURCE: 1999 buick park ave 3.8 reading a code po171

Hello Charley.
This code is most commonly set by an oxygen sensor that has become weak and is unable to generate enough voltage.
But it is possible that the engine actually is running lean and the sensor is doing it's job.
It is difficult to determine without the use of a scan tool that is capable of reading the data the sensor provides while it is running.
If the sensor is original and you have over a 100 k on the car I would recommend you change the sensor anyway.
90% chance it will fix the problem.
You will have 2 sensors on your car. You need the sensor on the engine side of the catalytic converter (bank1 sensor1)

SOURCE: my check engine light is on ran the code it is

check to make sure no vacuum leak as this will cause the code. check air filter is it dirty? if not on both the o2 sensor on bank one needs to be replaced. the will refer to this as the upstream o2 sensor its located on the rear of the engine in the exhaust manifold. hope this helps. dont know if this is a 3.8 or 3.1 so heres photos for both