Nissan Vanette 2012 P0171 OBD2 Code: Engine Air-Fuel Ratio Issue

My 2012 Nissan Vanette is showing a P0171 diagnostic trouble code, indicating an engine air-fuel mixture too lean. This code typically points to issues such as a faulty oxygen sensor, vacuum leak, or problems with the fuel delivery system. I've performed basic checks but need help identifying the root cause and potential fixes for this specific model.