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 wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
P0171Fuel System 1/1 LeanP0171Fuel system LeanP0171Fuel System 1/1 LeanP0171-00System Too Lean (Bank 1)View all · Manufacturer wording →
Manufacturer communications
327Original wording in English
JEEP
Reported code forms P0171 P0171-00
Not applicable to vehicles built for US market. Methanol In Fuel - Diagnostic Trouble Code (DTC) P0171 Customers may experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle may SYMPTOM: exhibit/set…
JEEP
Reported code forms P0171-00
Not applicable to vehicles built for US market. Flash: Powertrain Control Module (PCM) Updates Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of…
JEEP
Reported code forms P0171-00
Not applicable to vehicles built for US market. Flash: Powertrain Control Module (PCM) Updates *Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of…
JEEP
Reported code forms P0171-00
Not applicable to vehicles built for US market. Flash: Powertrain Control Module (PCM) Updates ustomers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the…
JEEP, RAM
Reported code forms P0171-00
Disconnected Purge Line Customers must experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle must exhibit/set one or more of the following Diagnostic Trouble Codes (DTCs): ● P0300-00 - Multiple…
FORD
Reported code forms P0171
This article supersedes TSB 23-2195 to update the labor times from M-time to fixed time. Some of the vehicles listed in the Model statement above may exhibit an illuminated MIL in the instrument panel cluster (IPC) with…
Check vehicle applicability
1,263A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Acura | ACURA | Year not specified |
| Acura | MDX | 2020 |
| Acura | MDX | 2019 |
| Acura | MDX | 2018 |
| Acura | MDX | 2017 |
| Acura | MDX | 2016 |
| Acura | RDX | 2020 |
| Acura | RDX | 2019 |
| Acura | RDX | 2018 |
| Acura | RDX | 2017 |
| Acura | RDX | 2016 |
| Acura | RLX | 2020 |
Historical records · 7 · Historical vehicle association; OBD-II compatibility is not established by this record.
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.