My diagnostic reader shows bank 1 is lean on my 1998 E150 van, what could this be?
Vacum leak, misfire, dirty air meter.
What is the code? Lean condition is too much air, like a vacuum leak, The pcm is trying to compensate by adding more fuel, causing you more grief.
O2 sensor possible
It is possible, but it would throw a code indicating a problem involving the 02 sensor. I wouldn't want to tell you to just replace it.
Looking for a Used E-150 in your area?
CarGurus has 169 nationwide E-150 listings and the tools to find you a great deal.
Search Ford E-150 Questions
Ford E-150 Experts