Audi B7 S4 ECS Assembled Heater Core Refresh Kit

The heater core is a heat exchanger, much like the radiator, that transfers heat from engine coolant to the air inside the vehicle's cabin. Clogged heater cores transmit heat poorly, while leaking heater cores drip engine coolant into the cabin, creating a bad odor and sometimes dampened carpeting.

If you are noticing a strong coolant odor while in the cabin of the vehicle, coolant loss without a visible leak, or poor heat output, chances are you have a bad heater core.

When replacing the heater core, there are one-time-use seals and clamps that also need to be replaced.