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
4Original wording in English
FORD
Reported code forms P0172
SOME VEHICLES MAY EXHIBIT VARIOUS DRIVEABILITY CONDITIONS INCLUDING LACKS POWER, HESITATES, HARD TO START, AND/OR MALFUNCTION INDICATOR LAMP (MIL) ILLUMINATED AND PRODUCE POSSIBLE DIAGNOSTIC TROUBLE CODES P0103, P0172…
FORD
Reported code forms P0172
SOME VEHICLES EQUIPPED WITH A 4.6L ENGINE A 5 SPEED MANUAL TRANSMISSION MAY EXHIBIT A SLIGHT HESITATION ON LIGHT TIP-IN ACCELERATION AND A MALFUNCTION INDICATOR LAMP ON WITH DIAGNOSTIC TROUBLE CODE P0172 AND P0175. *TT
FORD
Reported code forms P0172
VEHICLES EQUIPPED WITH A 4.6L ENGINE AND 5 SPEED MANUAL TRANSMISSION MAY EXHIBIT A SLIGHT HESITATION ON LIGHT TIP-IN ACCELERATION AND A MALFUNCTION INDICATOR LAMP ON WITH DIAGNOSTIC TROUBLE CODES P0172 AND P0175. *TT
FORD
Reported code forms P0172
SOME VEHILCES EQUIPPED WITH 4.6L ROMEO ENGINE AND MANUAL TRANSMISSION ONLY, MAY EXHIBIT A CHECK ENGINE LIGHT ON AND DIAGNOSTIC TROUBLE COE P0172 / P0175 STORED IN MEMORY WITH POSSIBLE DRIVEABLTILITY CONDITIONS SUCH AS…
Check vehicle applicability
5A 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.