P0174 GMC Sierra 1500
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 Sierra 1500 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 Sierra 1500.
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 Sierra 1500.
Common Causes on GMC Sierra 1500
- Bank 2 (passenger side) intake manifold gasket leak on 5.3L or 6.2L engine
- Cracked or disconnected vacuum hose on passenger side of intake
- Failing fuel injector on bank 2 cylinders causing lean condition
- Mass airflow sensor contaminated or reading low
- PCV valve stuck open causing excessive crankcase ventilation
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 Sierra 1500
On 5.3L V8 engines, intake manifold gasket leaks on bank 2 are extremely common after 80k miles. Always check both banks when this code appears.