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1.5 km of travel after a cold start may be enough time for the engine to switch from open loop mode to closed loop mode in regards to engine control strategy after the A/F ratio sensors reach operating temperature which is 1200 degrees. If you had an O2 sensor replaced, it would be behind the catalytic converter because I know BMW uses A/F ratio sensors upstream so I believe you have an A/F sensor is bias rich on bank 1 which includes the first 3 cylinders. - 11% is considered fine for some vehicle makes but will trip a code when the combined ST and LT fuel trims pass a threshold
If you want more help diagnosing the problem, send me the A/F voltage readings when your engine reaches operating temperature or when the problem occurs and we can determine if this is your issue.
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