P0174 Code: System Too Lean (Bank 2)
🟠 Moderate severity · drivable
Same as P0171 but on bank 2. Drivable short-term; a lean condition should be fixed soon.
What P0174 means
The engine is running lean on bank 2 — too much air or not enough fuel. It's the bank 2 version of P0171: the computer hit its fuel-trim limit trying to compensate.
Symptoms
- Check engine light is on
- Rough or surging idle
- Hesitation or lack of power
- Poor fuel economy
- Possible stalling
Common causes
- most common: Vacuum leak (cracked hose or leaking intake gasket)
- common: Dirty or failing mass air flow (MAF) sensor
- common: Weak fuel pump or clogged fuel filter
- less common: Faulty upstream oxygen sensor (bank 2)
- less common: Leaking fuel injector or intake manifold gasket
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Inspect and repair vacuum leaks (hoses, intake boot, gaskets) | Yes | $10–100 |
| Clean the mass air flow sensor with MAF cleaner spray | Yes | $10–20 |
| Replace the upstream oxygen sensor if it's reading incorrectly | Yes | $60–200 |
| Replace a weak fuel pump or clogged fuel filter | Mechanic | $300–800 |
Frequently asked questions
What does bank 2 mean?
Bank 2 is the side of the engine that does not contain cylinder 1. On most engines it's simply the opposite cylinder bank from bank 1.
What's the most common cause of P0174?
A vacuum leak is the most common cause, followed by a dirty or failing MAF sensor.
Will P0174 clear itself?
Not permanently. The underlying lean condition needs to be found and fixed; the light will usually return until it is.
Related codes
P0171
P0171 Code: System Too Lean (Bank 1)
P0101P0101 Code: Mass or Volume Air Flow (MAF) Sensor Circuit Range/Performance
P0300P0300 Code: Random/Multiple Cylinder Misfire Detected
P0174 by vehicle brand
Causes and repair costs for P0174 differ between makes. Pick your brand for the specifics.
Toyota
P0174 on a Toyota
HondaP0174 on a Honda
FordP0174 on a Ford
ChevyP0174 on a Chevy
NissanP0174 on a Nissan
BMWP0174 on a BMW
Mercedes-BenzP0174 on a Mercedes-Benz
VolkswagenP0174 on a Volkswagen
HyundaiP0174 on a Hyundai
SubaruP0174 on a Subaru
MazdaP0174 on a Mazda
JeepP0174 on a Jeep
GMCP0174 on a GMC
LexusP0174 on a Lexus
VolvoP0174 on a Volvo
Related guide: MAF Sensor Replacement Cost →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.