my car has code p171 and p174 on 2003 Ford Windstar

I want to know what is that.

Asked by for the 2003 Ford Windstar
Both codes indicate o2 sensors are staying at a low voltage theshold. Vacuum leaks on this engine are common. Upper intake manifold grommets and bolts have a update design to combat this problem. Have a reliable shop check your car for this.