What does this code mean?
P0171/P0172 refer to bank 1; P0174/P0175 to bank 2. Lean or rich describes the controller's mixture assessment, not a direct measurement of a failed part. Compare fuel trims at idle and under load, inspect air and exhaust leaks, and test fuel supply or sensor readings using vehicle-specific limits.
Sources and interpretation [1]
A code identifies a detected condition, not a part that must automatically be replaced.
Manufacturer communications
5Original wording in English
FORD
Reported code forms P0172
Certain 2020-2021 Model Year Transit Vehicles Equipped with a 3.5L Ecoboost Engine - Fuel Filler Door E85 Label Removal .In all of the affected vehicles, the fuel tank filler door may incorrectly have an E85 fuel label…
FORD
Reported code forms P0172
Certain 2020-2021 Model Year Transit Vehicles Equipped with a 3.5L Ecoboost Engine - Fuel Filler Door E85 Label Removal - In all of the affected vehicles, the fuel tank filler door may incorrectly have an E85 fuel label…
FORD
Reported code forms P0172
Some 2015-2018 Transit vehicles built on or before 24-Jul-2018 may exhibit various drivability concerns including difficulty starting, misfires and/or an illuminated MIL with diagnostic trouble codes (DTCs) P00BD,…
FORD
Reported code forms P0172
Some 2015-2018 Transit vehicles built on or before 24-Jul-2018 may exhibit various drivability concerns including difficulty starting, misfires and/or an illuminated MIL with diagnostic trouble codes (DTCs) P00BD,…
FORD
Reported code forms P0172
SOME 2015 TRANSIT VEHICLES BUILT ON OR BEFORE 30-MAR-2015 MAY EXHIBIT VARIOUS DRIVABILITY CONCERNS INCLUDING DIFFICULTY STARTING, MISFIRES AND/OR AN ILLUMINATED MALFUNCTION INDICATOR LAMP (MIL) WITH DIAGNOSTIC TROUBLE…
Check vehicle applicability
6A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Sources and interpretation
These explanations are editorial summaries of the linked manufacturer material. PDF page numbers count from the first file page. Original publications are in English; translations are reference aids. A cited edition is not a claim that it is the manufacturer's latest instruction.
- 2024–2025 MY OBD System Operation Summary for Gasoline Engines ↗
Ford Motor Company · PDF page(s) 21, 22 ·
Source check date · 2026-10-27
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.