What does code P1138 mean on BMW vehicles?
The heater circuit of the downstream oxygen sensor on bank 1 reports low voltage.
OBD-II Code BMW
P1138 — BMW — Oxygen Sensor Heater Circuit Low Voltage (Bank 1 Sensor 2)
The heater circuit of the downstream oxygen sensor on bank 1 reports low voltage.
Common symptoms
- Check engine light on
Possible causes
- Low battery voltage
- open circuit
Initial recommendation
Inspect power supply and wiring to the oxygen sensor heater.
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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