P0171 2000 Honda Accord

Question

What can I do to correct it

Answer 1

P0171 Fuel trim lean

Is there any vacuum leaks? Vacuum leaks are some of the main cause for a lean fuel trim so those  should be check especially the PVC valve and the hose.

 Here is Hoda Civic that had a lean fuel trim. all the vacuum hose where secure and no leaks found , when the sparkplugs where check all where secured except for the number 4 cylinder, being loose in the sparkplug chamber prevented it from properly sealing. this vehicle recently had a tune up performed and there was no CK ENG LT prior to the sparkplug replacement , it did not set a misfire code just a lean code P0171, retorque the sparkplug and that  corrected P0171