P0174 Toyota Highlander
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 Toyota Highlander 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 Toyota Highlander.
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 Toyota Highlander.
Common Causes on Toyota Highlander
- Intake manifold gasket leak on bank 2 of 3.5L V6
- Air induction hose crack on passenger side of engine
- Bank 2 fuel injector restricted or failing
- PCV valve stuck open on passenger valve cover
- Exhaust manifold crack on bank 2 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 Toyota Highlander
RAV4 4-cylinder models will not set P0174 as they only have one bank. Highlander and Venza V6 models are prone to intake gasket issues.