System Too Lean (Bank 2)
Fuel System · Air/Fuel Mixture
Bank 2 is running lean — too much air relative to fuel. Mirror of P0171 but affects the passenger side bank on V6/V8 engines.
- Vacuum leak Bank 2 intakeMost common
- Dirty MAF sensorMost common
- Clogged fuel injectorsCommon
Vehicles most commonly affected by P0174
P0174 (Bank 2 lean) is most commonly reported on V6 and V8 engines. Ford F-150 5.4L and 4.6L 3-valve Triton engines have a well-documented intake manifold gasket failure that causes both P0171 and P0174 simultaneously. GM 5.3L V8 engines frequently develop P0174 from dirty MAF sensors. Toyota Sienna and Tundra V6 models commonly show P0174 from rear bank vacuum leaks.
Real-world P0174 diagnosis scenario
A 2005 Ford F-150 4.6L stores both P0171 and P0174. The technician checks fuel trims: Bank 1 LTFT +16%, Bank 2 LTFT +18% — both elevated identically. This symmetric pattern immediately points to a shared cause rather than bank-specific components. A smoke test reveals a cracked intake manifold gasket — a known failure point on the 4.6L and 5.4L Triton engines. Intake manifold gasket replacement ($350–$600 at a shop) resolves both codes.
When P0171 and P0174 appear together with similar fuel trim values on both banks, start with the MAF sensor and intake manifold before checking bank-specific components. Symmetric lean conditions almost never originate from a single bank component.
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Frequently asked questions about P0174
What does P0174 mean?
Bank 2 is running lean — too much air relative to fuel. Mirror of P0171 but affects the passenger side bank on V6/V8 engines.
Is P0174 serious?
Drive with caution — lean conditions can damage engine over time.
How much does it cost to fix P0174?
Repair costs for P0174 range from $75 – $250 depending on the root cause and your vehicle.
Can I drive with P0174?
You can drive short distances but should have it repaired within 1–2 weeks to prevent further damage.
What is Bank 2 on a Ford F-150?
On the F-150 V8 (4.6L and 5.4L), Bank 2 is the passenger side of the engine. On the EcoBoost V6, Bank 2 is the rear bank.
Can P0174 alone (without P0171) mean something different?
Yes. P0174 alone (Bank 2 only, with Bank 1 normal) points to a bank-specific issue: a vacuum leak on the passenger side intake, a failing fuel injector on Bank 2, or a Bank 2 MAF issue on dual-MAF systems.
How do I know if my MAF sensor needs cleaning or replacement?
Clean it first with MAF cleaner spray ($10). If fuel trims normalize after cleaning, the sensor was dirty. If they return to elevated within 1,000 miles, the sensor element is damaged and needs replacement ($100–$300).