What does code P1178 mean on BMW vehicles?
The upstream oxygen sensor on bank 1 switches too slowly from rich to lean conditions.
OBD-II Code BMW
P1178 — BMW — Oxygen Sensor Signal Circuit Slow Switching from Rich to Lean (Bank 1 Sensor 1)
The upstream oxygen sensor on bank 1 switches too slowly from rich to lean conditions.
Common symptoms
- Slow mixture adjustment
Possible causes
- Faulty oxygen sensor
Initial recommendation
Replace oxygen sensor and verify fuel control response.
Safety notice
This information is for guidance only. Brand-specific codes may vary by model, year, engine, transmission and vehicle configuration. It does not replace a physical inspection or diagnosis by a qualified mechanic. If the vehicle is unsafe to operate, avoid driving it and seek professional inspection.
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