P0171 on Lexus vehicles The engine is running lean on bank 1: too much air, or not enough fuel, for the mixture the computer wants

A model year is listed because the code is named in its own record — a bulletin filed against it, or an owner’s complaint about it — not because every one of these vehicles sets it. Counts are documents in NHTSA’s files, not failure rates.

Bulletins and campaigns Lexus filed with NHTSA whose summary names P0171. Quote the document number at the service desk — it is a diagnosis the maker has already written down.

• LSB000523 Service bulletin
  2023-02-09 · Electrical System — Instrument Panel — Fuel Gauge
• TSB: Some 2013 ? 2020 model year Lexus vehicles may exhibit a hard start and/or MIL ON condition with one or more of the following Diagnostic Trouble Codes (DTCs): ?DTC P0171 and/or P0174 (System Too Lean Bank 1/Bank 2) ?DTC P0087 Fuel Rail / System Pressure ? Too Low Techstream data list analysis may reveal positive fuel trims including a no pressure condition verified by a manual fuel pr

A stored code names the test that failed, never the part that caused it. The record above is what Lexus and its owners have filed about it; the code’s page across every make has the whole file.