Got a P0171 code on E46 Bmw 2001, it's been on for about 6 months.

Question

Not sure where to start looking on this one, anybody been able to sort this one out?
Car starts and runs good, no noticeable power loss and fuel consumption about 28 to 30 Mpg around town.

Answer 1

P0171 Fuel trim system lean Bank1

Vacuum leak are the most common cause of lean bank code, this should be done first, especially at the MAF air duct which tends to rip there ,