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.
P0174System Too Lean Bank 1/Bank 2P0174System too Lean Bank 1/ Bank 2P0174System too Lean Bank 1/Bank 2P017400System Too Lean Bank 2Manufacturer communications
11Original wording in English
TOYOTA
Reported code forms P017400
Some 2023 – 2024 model year Sequoia Hybrid and 2022 – 2024 model year Tundra and Tundra Hybrid vehicles may exhibit lack of power during acceleration and/or a MIL ON condition with one or more of the following…
TOYOTA
Reported code forms P017400
TSB: Some 2023 model year Sequoia Hybrid and 2022 ? 2023 model year Tundra and Tundra Hybrid vehicles may exhibit poor acceleration and/or a MIL ON condition with one or more of the following Diagnostic Trouble Codes…
TOYOTA
Reported code forms P0174
TSB: Some 2014 ? 2020 model year Toyota 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…
TOYOTA
Reported code forms P017400
TT: Some 22MY Tundra/HV vehicles may experience a MIL ON w/DTC(s) P017400, P043000. Other symptoms of this issue include poor acceleration. A lean condition may cause damage to the internal catalyst in the catalytic…
TOYOTA
Reported code forms P0174
TSB: REVISION NOTICE January 23, 2020 Rev1: G1439 The Parts Information, Calibration Information, and Repair Procedure sections have been updated. SUPERSESSION NOTICE The information contained in this bulletin…
TOYOTA
Reported code forms P0174
TSB: SUPERSESSION NOTICE The information contained in this bulletin supersedes Service Bulletin No. T-SB-0058-13. Service Bulletin No. T-SB-0058-13 is obsolete and any printed versions should be discarded. Some 2009 ?…
Check vehicle applicability
17A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Toyota | TUNDRA | 2024 |
| Toyota | TUNDRA | 2023 |
| Toyota | TUNDRA | 2022 |
| Toyota | TUNDRA | 2020 |
| Toyota | TUNDRA | 2019 |
| Toyota | TUNDRA | 2018 |
| Toyota | TUNDRA | 2017 |
| Toyota | TUNDRA | 2016 |
| Toyota | TUNDRA | 2015 |
| Toyota | TUNDRA | 2014 |
| Toyota | TUNDRA | 2013 |
| Toyota | TUNDRA | 2012 |
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.