Fuel trim and air/fuel mixture
P0174
System Too Lean (Bank 2)
What does P0174 mean?
P0174 is the bank 2 version of P0171 — the engine computer has been adding extra fuel for too long to correct a mixture it reads as too lean on the second cylinder bank. It only appears on engines with two banks. Seeing P0171 and P0174 together points at a shared cause rather than one bank.
Can I keep driving with P0174?
Moderate urgency
When P0171 and P0174 appear together, look for one shared cause upstream — a single vacuum or airflow problem is far more likely than two separate bank faults.
Symptoms of P0174
Rough idle, sometimes only when cold
Hesitation under acceleration
Check engine light, frequently paired with P0171
Common causes of P0174
A vacuum leak large enough to affect both banks
A dirty or failing mass airflow sensor
Low fuel pressure affecting the whole engine
A failing PCV valve or intake manifold gasket
These are ordered roughly by how often they turn out to be the cause — but the code names a system, not a part. Confirming which one is yours takes data from the running engine.
What does it cost to fix P0174?
$100 – $900
Typical US independent-shop range, parts and labour included. It is wide on purpose: the cheap end is usually a sensor, a hose or a cap, and the expensive end is the major component the code was reporting on. Which one you need is a diagnosis, not a guess — and dealer rates run higher than these figures.
What does P0174 mean for your car?
This page explains what P0174 means in general. It cannot tell you which of those causes is yours, because that answer is in your car's own data. Kaiju Mechanic reads the codes your car is actually storing, plus live sensor data through any standard ELM327 adapter, and interprets it against your exact year, make, model and mileage. You can also just ask it about P0174 in chat — no adapter needed for that.
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