BMW fault code 12B302

12B302 is a fault stored in your BMW's memory (an ISTA fault code, not a standard OBD-II P-code).

What it means:
Oxygen sensor heater after the catalytic converter: short circuit to ground (OBD-II P0037). Usually chafed or melted wiring to the rear lambda sensor; less often a burnt-out heater inside the sensor or a blown fuse.

Related codes: 120308 · 120408 · 121001

Decode your BMW's fault memory automatically in Telegram

Free reference for owners. Not affiliated with BMW AG; BMW and CarData are trademarks of BMW AG.