OBD codes / P0174
P0174
SeriousSystem Too Lean (Bank 2)
P0174 is usually safe to drive with short-term, but don't ignore it. A lean mixture runs hotter and can eventually trigger misfires. Have it diagnosed soon — and because a cheap vacuum leak and an expensive fuel pump both set this code, confirm the cause before buying parts.
What this code means
P0174 is the Bank 2 twin of P0171: too much air or too little fuel on the side of the engine with cylinder 2, and the computer has hit its limit adding fuel to compensate. The most common cause is unmetered air — a vacuum or intake leak, or a dirty mass-airflow (MAF) sensor under-reporting airflow. It can also be weak fuel delivery: a tired fuel pump, a clogged filter, or dirty injectors. When P0171 and P0174 appear together, the cause is usually something shared by both banks (the MAF or fuel supply) rather than one isolated leak.
Symptoms you might notice
- Rough or unstable idle
- Hesitation, stumble, or lack of power under acceleration
- Slightly reduced fuel economy
- Occasional surging at steady speed
- Sometimes no symptom beyond the check-engine light
What it costs to fix
Typical range: $100–$1,000 · about ~0.3–3 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Vacuum / intake leak repair (hose, gasket, PCV) | $10–$150 | ~0.5–2 hrs |
| MAF sensor (clean or replace) | $0–$350 | ~0.3–0.5 hrs |
| Fuel pump | $150–$500 | ~1–3 hrs |
| Fuel filter | $20–$120 | ~0.5–1.5 hrs |
A vacuum-leak or MAF-clean fix is often under $200; a fuel pump is the expensive end. If P0174 shows up alongside P0171, suspect a shared cause (MAF or fuel supply) rather than two separate leaks.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0174 for my exact vehicle →
Frequently asked
Can I drive with P0174?
Short-term, usually yes — it's rarely an immediate breakdown risk. But a lean condition runs the engine hot and can lead to misfires over time, so have it diagnosed soon.
Why do I have both P0171 and P0174?
Both banks reading lean at once usually points to a cause they share — most often the MAF sensor or the fuel supply (pump, filter, pressure) — rather than a vacuum leak on just one side. That actually narrows the diagnosis.
Will cleaning the MAF fix P0174?
Sometimes — a dirty MAF is a common, cheap cause. But if a vacuum leak or fuel-delivery problem is the real issue, cleaning won't help, so verify before assuming.
How much does it cost to fix P0174?
Often inexpensive — many fixes are a hose, a gasket, or a MAF clean for well under $200. It only gets costly if the cause is a fuel pump. Confirm the cause first.
Seeing P0174 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0174 for my vehicleGeneric OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.