My son's '99 XLS 4.0 (cheaper engine, I think) with 97K miles has been showing P0171 and P0174 codes for the last several months. (just came home from college today) He has been getting them reset (cleared) and after several days they come back on.
Car history: Bought new in '98 and treated well. NO work of any kind has been required under the hood.
He says it has not affected the performace of his Explorer and it doesn't have any problems or run rough starting in cold weather. He also left my Haynes repair manual at school. I think this is the OHV version? Most if not all of the post refer to the SOHC model.
What should I start to do since he will be home for only a few days? Any help would be appreciated.
/Richard