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      01-21-2020, 10:23 AM   #8
Theodore
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Drives: 2011.5 E92 M3
Join Date: Oct 2015
Location: Tampa Bay, FL

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Quote:
Originally Posted by Helmsman View Post
Hi guys, creating a new thread hoping for feedback on this.

Had the A6D1 code coming and going but now seems not possible to clear any longer. As the "Rest heat" button was taken away from 2010 year model, my understanding is that the ignition have to be on to make the pump run. Makes me wonder about the function, and need to replace the pump at all.

Anyone with more insight in this function?

Thanks
In the past I read the auxiliary water pump is intended to circulate coolant between the engine and the heater core before the thermostat opens up the connection between the engine and radiator. You can see how this is done in the diagram below. This gets you heat inside the cabin earlier than if you didn't have it at all. The electronic control of the auxiliary pump may have an additional benefit that the car can probably custom regulate the flow of coolant through the heater core to make interior cabin heat control a smoother operation, though I'm not positive BMW takes advantage of that.

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