Essentially this means the engine is running with too much air and not enough fuel. This typically turns out to be an air leak.
How to fix bank 1to lean on a 3100 v6
P0171 System too Lean (Bank 1)
If you are getting codes for bank 1 and bank 2 lean, then yes it is a possibility.
lean bank 1 lean bank 2 fuel trim limits reached
what does system to Lean Bank 1 on 740iL 2001 means
po171--- system to lean (bank # 1)
1999 Ford Taurus. System Adaptive fuel too lean banks 1 and 2. How can I fix these.
That means that your o2 sensor is stuck lean (bank 1 sensor 1)
Trouble code P0171 means:System too lean (Bank 1)
Trouble code P0171 means:System too lean (Bank 1)
Trouble code P0171 means:System too lean (Bank 1)
Bank 2 running too lean.