Check this first
Same checks as bank 1 – if both banks are lean, look for one shared leak or a fuel supply problem.
What usually fixes it
In the order a good shop checks them. Typical total: $67–$1,006 at $130 an hour.
Vacuum or intake leak
$171–$444A leak in a shared pipe shows on both banks at once.
Air flow sensor
$112–$401One sensor feeds both banks, so it upsets both.
Fuel pressure or injectors
$410–$1,006A tired pump leans out both sides under load.
Code titles are the generic SAE definitions. Prices are typical US parts and labor for a common car or light truck – a guide for judging a quote, not a quote. Always confirm a repair against the vehicle in front of you.