kurtdimpel

My 2001 windstar engine code is showing banks 1 + 2 are running lean. I have changed the fuel filter and spark plugs. The check engine light comes on about 2 days after I reset it. Is ther another sensor or is the main computer having issues? Help

gw.belden

If the codes are PO171 and PO174 there is a TSB on this and you have to replace some bolts in the plenum and possibly the left [front] valve cover. There are a lot of postings on this extremely common Windstar problem. I found the TSB info on Alldatadiy. I did it and the lean conditions came back. Then I discovered a cracked flex hose on the exhaust side allowing oxygen to enter the exhaust, fooling the O2 sensor into thinking "lean". Fixed the flex hose and error code never came back....