P0174 — System Too Lean (Bank 2)
Drive with caution — fix soon.
What P0174 means
P0174 means the engine is running too lean on bank 2, with too much air or not enough fuel in the mixture. The computer is adding extra fuel to compensate but still can't reach the right balance. Bank 2 is the side of the engine that does not contain cylinder 1, so this code only appears on engines with two cylinder banks like V6 and V8.
Common symptoms
- Check engine light on
- Rough or unstable idle
- Hesitation or weak acceleration
- Occasional misfire or surging
- Reduced fuel economy
Common causes
- Vacuum or intake air leak on bank 2
- Dirty or faulty mass airflow (MAF) sensor
- Weak fuel pump or clogged fuel filter
- Clogged fuel injectors
- Leaking PCV or intake gasket
- Faulty oxygen sensor on bank 2
Typical repair cost
$100 – $550
Varies by vehicle and root cause.
Frequently asked questions
Can I drive with P0174?
Usually yes, in the short term, but don't put off the repair. A lasting lean condition can cause misfires and added heat, so have it checked soon.
How much does it cost to fix a P0174?
It depends on the cause: a vacuum leak or MAF cleaning may be $100-$250, while a fuel pump or injector repair can reach $300-$550 or more.
Is a P0174 serious?
It's moderate. It won't usually strand you immediately, but a prolonged lean mixture can lead to misfires and wear, so it shouldn't be ignored.
What's the difference between P0174 and P0171?
They're the same lean condition but on different sides of the engine: P0171 is bank 1 and P0174 is bank 2. Seeing both together often points to a shared cause like a big vacuum leak or a faulty MAF sensor.