P0174: System Too Lean (Bank 2)
P0174 mirrors P0171 on the second cylinder bank. Often paired with P0171 when the cause is a vacuum leak.
Severity: moderate · System: Powertrain · Safe to drive: usually, short-term. Same as P0171 — not immediately dangerous but shouldn't be ignored.
Symptoms
- Rough idle
- Poor acceleration
- Occasional stalling
Common causes
- Vacuum leak on bank 2
- Dirty MAF sensor
- Fuel delivery issue
Fair repair prices
| MAF cleaning + intake inspection | $60–$180 |
|---|---|
| Vacuum leak repair | $100–$400 |
| Fuel pressure test + repair | $150–$900 |
Ranges are US market averages (parts and labor). If your shop's quote is above the high end, ask for a line-item breakdown or run it through the invoice checker.
Other codes
- P0300 — Random / Multiple Cylinder Misfire Detected
- P0301 — Cylinder 1 Misfire Detected
- P0420 — Catalyst System Efficiency Below Threshold (Bank 1)
- P0430 — Catalyst System Efficiency Below Threshold (Bank 2)
- P0171 — System Too Lean (Bank 1)
- P0442 — Evaporative Emission Control System Leak (Small)
- P0455 — Evaporative Emission Control System Leak (Large)
- P0128 — Coolant Temperature Below Thermostat Regulating Temperature