P0173
Fuel Trim Malfunction (Bank 2)
System: Air/Fuel
Severity: medium
What does P0173 mean?
The DTC P0173 (Fuel Trim Malfunction (Bank 2)) is a fault code stored by the ECU when it detects a fuel trim B2 fault 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 P0173
- Vacuum leak bank 2
- Failed B2 O2
- Injector imbalance B2
- Bank 2 exhaust leak
How to fix P0173
Smoke test bank 2 intake. Compare LTFT B1 vs B2 — divergence = mechanical issue, not tuning.
Tuning approach with DaVinci Deluxe
For P0173, DaVinci Deluxe offers the following ECU map adjustments and software solutions:
- Per-bank fuel trim adjust
- B2 lambda target
Need to fix P0173 on your ECU?
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