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.
P0172Fuel Trim System RichManufacturer communications
26Original wording in English
BUICK, CHEVROLET, GMC
Reported code forms P0172
This document provides the technician with a diagnostic tip if the vehicle stalls and set diagnostic trouble code P0191 and may also set P0172. The diagnostic tip has the technician inspect the high pressure fuel pump…
CHEVROLET, GMC
Reported code forms P0172
This service bulletin provides a repair procedure to correct a customer concern of Reduced Engine Power, Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0101, P0172, P0299, P0506, and/or P1101 Set.
CHEVROLET, GMC
Reported code forms P0172
This Preliminary information communicates the possibility of the charge air cooler pipe connection becoming disconnected from the throttle body causing a reduced power issue and one or more of the following trouble…
CHEVROLET, GMC
Reported code forms P0172
This Preliminary information communicates the possiblilty of the charge air cooler tube becoming disconnected from the throttle body and causing reduced power with dtc P0172 P0299 P0101 P0506 P1101
BUICK, CHEVROLET, GMC
Reported code forms P0172
This service bulletin provides a repair procedure to correct a customer concern of a MIL Illuminated with DTC P0172, P06DE and/or P0521 Set.
BUICK, CADILLAC, CHEVROLET, GMC
Reported code forms P0172
This service bulletin provides repair procedures, depending on model year, to correct a customer concern of a Malfunction Indicator Lamp (MIL) Illuminated with DTC P0172, P06DE and/or P0521 Set.
Check vehicle applicability
13A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| GMC | TERRAIN | 2022 |
| GMC | TERRAIN | 2021 |
| GMC | TERRAIN | 2020 |
| GMC | TERRAIN | 2019 |
| GMC | TERRAIN | 2018 |
| GMC | TERRAIN | 2017 |
| GMC | TERRAIN | 2016 |
| GMC | TERRAIN | 2015 |
| GMC | TERRAIN | 2014 |
| GMC | TERRAIN | 2013 |
| GMC | TERRAIN | 2012 |
| GMC | TERRAIN | 2011 |
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.