2008 f150 fx4 5.4.... I know my f150 has 4 02 sensor's. 2 upstream and 2 downstream. Are they all the same motorcraft part # ? How many mile's before these go bad?(Cel on) Bank 1 lean and im thinking of putting new upstream sensor in.

 

I think the part number may be different but if I remember right it is the length of the leads that is different. There are different opinions on this but 100k is a good life for an O2 sensor. Stick with motorcraft replacements and have fun getting the up stream ones out.