I had continual o2 heater errors until I managed to recalibrate the heater circuit.

I started the car twice with the two replaced rear sensors unplugged. Got a handful of error codes. Plugged them back in, reset the codes, no more codes related to the o2 heaters after that.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)