AI4Car quick readA short, original guide from the AI4Car knowledge library.
P0171 means the system detected a lean condition on Bank 1 under the monitor's test conditions. Check whether P0174 is also present and note whether the issue is strongest at idle or under load.
Cracked intake hoses, unmetered air, fuel delivery, and sensor errors can produce overlapping clues. Inspect and test the air path before treating the oxygen sensor as the automatic fix.
Quick educational note
For information, not a diagnosis or repair instruction. Vehicle-specific checks are still required. Consult the manufacturer's guidance and a qualified technician.
How to use this information
This article explains general principles and does not establish what is wrong with your vehicle. Read the content limitations.