Where are oxygen sensors located on a Ford Windstar LX?

There are 2 oxygen sensors one upstream and one down stream. Both oxygen sensors are located underneath the van. The down stream oxygen sensor is located behind the cataylic converter near the cross pipe and the upstream oxygen sensor is located in front of the cataylic converter in plain sight. They look like spark plugs with either 8", 12", or 14" wires attached to them. The upstream oxygen sensors is easily located underneath the vechicle to the front. The downstream oxygen sensor is not the one lcoated on or close to the cataylic converter.