There’s a little radiator about the size of a shoebox hiding in your dashboard. It’s your BMW Heater Core, and it’s what keeps you toasty warm on those frigid winter mornings. When you select heat on your climate control system, a small valve opens under the hood. That valve lets hot water from your engine’s cooling system travel into the heater core under your dash. Just like the radiator in the engine bay, the heater core has lots of fins that transfer the heat from the water to the surrounding air. But instead of exhausting that hot air to the outside, your climate control system blows it through your interior.

Your first thought may have been that it seems dangerous to have hot water circulating through your leather and suede interior. Fortunately, it’s rare that a heater core bursts with enough force to actually cause damage or injury. But, like the radiator, your BMW heater core can leak and make a mess of the interior. If you notice a sweet odor in your car accompanied by dampness on your carpets, turn off the heat and get your BMW heater core checked out immediately. You can avoid further damage by acting quickly.