Check Engine - P0170

[saintpi]

I get ocasional "check engine". Using an OBD2 TekLink equipment, I'm able to diagnose fault to P0170 code which means "Fuel Trim (bank 1)"
:?: What does this really mean? How can I solve the problem. Thanks :!: I have a 97 Galant.

[bronxbombr]

O2 sensor, if you need it let me know. I have many in stock all day everyday.

[FrankMB]

or a dirty/defective MAF