P0174
System Too Lean (Bank 2)
System: Air/Fuel
Severity: medium
What does P0174 mean?
The DTC P0174 (System Too Lean (Bank 2)) is a fault code stored by the ECU when it detects a lean B2 condition in the air/fuel subsystem. It is commonly seen on European and Asian vehicles using Bosch, Continental, Siemens or Denso ECUs.
Common causes of P0174
- Vacuum leak on bank 2
- Failed B2 fuel injector
- Bank-specific exhaust leak before O2
- Low fuel pressure (both banks affected normally — check if only B2)
How to fix P0174
Same diagnosis as P0171 but B2. If both P0171+P0174 → fuel pressure / pump / filter.
Tuning approach with DaVinci Deluxe
For P0174, DaVinci Deluxe offers the following ECU map adjustments and software solutions:
- LTFT recalibrate B2
- Injector size scaling
- Per-bank lambda tune
Need to fix P0174 on your ECU?
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