After the car is shut off, the coolant pump will stop with the car but after a min the car will stay off but the coolant pump will kick on. Runs until battery is drained. I do understand there is a feature to circulate the coolant so help mitigate burn/hot spots but this continues until the battery is disconnected by ECU. Then it won't start because the battery is too low. Ongoing issue for the past 2 years now, happens intermittently. Frequency is random but happens more when it's cold out. But average happens...
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a few times a week when cold out, sometimes it runs well for a few weeks then starts happening again. We had tried to troubleshoot by BMW but no luck. They have replaced battery, alternator, have tried to diagnose about 4 times now but they haven't fixed it since they can't replicate at the BMW Shop. I can hear the coolant pump running as well as feel the water moving. Also tested by Fluke Meter, it drains at about 40 amps (at 12 volts) when this happens, with the car off. Doing anything (opening doors, trunks, locking, unlocking, stops it for a minute but then pump starts again). No errors pop up for it except when the battery is low and then error battery had high discharge pops up.