OBD-II code · Powertrain (generic)
P0174 System Too Lean (Bank 2)
Same condition as P0171 but on bank 2 of a multi-bank engine (V6, V8, flat-six, etc.). When P0171 and P0174 appear together, the cause is usually a shared component such as the MAF sensor or a central vacuum leak rather than a bank-specific fault.
Is it safe to drive with P0174?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyCentral vacuum leak (intake manifold gasket, brake booster)
- Most likelyMAF sensor contaminated
- PossibleFuel pressure low (affects both banks)
Symptoms
- Check engine light on
- Rough idle, possible stalling
- Hesitation or hard cold start
- Power loss under load
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–4 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Intake Manifold, Mass Air Flow Sensor, Fuel Pump, Fuel Pressure Regulator
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.