how to fix code p0171 for 2003 Ford Expedition?

Question

I CHANGED OUT THE CO2 SENSOR AND STILL HAS THE SAME CODE.

Answer 1

P0171 Fuel trim lean (bank 1)

This 02 sensor detects the engine condition ,having a lean bank code can be from a MAF (mass airflow) ,do a MAF cleaning on the mass airflow, and the fuel pressure will need to be check, the specification are key on engine off 55psi, engine running is 55 psi.