P0174 GMC Terrain
System Too Lean (Bank 2) · Powertrain Code · High · Repair: Moderate
What is P0174?
The engine is running lean on bank 2. Same causes as P0171 but affecting the opposite cylinder bank on V-engines.
When the GMC Terrain triggers code P0174 (system too lean (bank 2)), it typically points to an issue in the powertrain system. This is a high severity code, so address it promptly to avoid further damage or safety concerns. Below you'll find the most common causes, symptoms, and repair options specific to the GMC Terrain.
This repair is rated moderate, meaning some experience and specialty tools required.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your GMC Terrain.
Common Causes on GMC Terrain
- Cracked intake boot between throttle body and airbox on 1.5T engine
- Vacuum leak at brake booster hose connection
- Fouled or failing fuel injector on bank 2 of 3.6L V6
- Mass airflow sensor reading low due to contamination
- Exhaust leak before bank 2 O2 sensor causing false lean reading
Symptoms
- Rough idle especially when cold
- Hesitation or stumble on acceleration
- Engine surging at steady throttle
- Lean misfire under load
- Poor fuel economy
- Check engine light illuminated
Notes for GMC Terrain
P0174 is uncommon on 4-cylinder Equinox models as they only have one bank. On 3.6L V6 models check the intake manifold gaskets.