The Nissan Path

Hi ,once a week more less p0171 keep coming after clearing the code every time.
2008 Pathfinder V6 122000 miles
(2) Is clearing the ECU with a code reader is the same as reset the ECU by disconnect the battery?
Thank.

I think it may forget more of your fuel trim info, so it might take longer for the code to come back, but it won't fix anything. Does your reader show live data?