What P0174 means
Same lean condition as P0171 but on the second cylinder bank. P0171 and P0174 together point at a shared cause such as the MAF sensor or a central vacuum leak.
Common causes
- Vacuum leak
- MAF sensor contamination
- Low fuel pressure
- Failed PCV valve
How it is usually fixed
- 1Smoke-test the intake
- 2Clean the MAF
- 3Test fuel pressure
- 4Inspect the PCV system
Other common codes
- P0011 — Camshaft Position A – Timing Over-Advanced (Bank 1)
- P0030 — HO2S Heater Control Circuit (Bank 1, Sensor 1)
- P0101 — Mass Air Flow Circuit Range/Performance
- P0113 — Intake Air Temperature Sensor Circuit High
- P0118 — Engine Coolant Temperature Sensor Circuit High
- P0131 — O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)
Code information is general guidance, not a diagnosis for a specific vehicle. Confirm with live data and manufacturer test procedures before replacing parts.