P0174 Mazda Cx-5
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 Mazda Cx-5 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 Mazda Cx-5.
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 Mazda Cx-5.
Common Causes on Mazda Cx-5
- Intake manifold gasket leak causing vacuum leak
- PCV valve failure in valve cover assembly
- Mass airflow sensor contamination or failure
- Vacuum hose crack at brake booster connection
- Fuel injector carbon deposits from direct injection
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 Mazda Cx-5
P0174 is uncommon on 4-cylinder Skyactiv engines as they only have one bank. CX-5, CX-50, Mazda3, and CX-30 use inline-4 engines where only P0171 applies.