Heater circuit function diagram showing coolant flow through engine, thermostat, heat exchanger, expansion reservoir, and radiator circuits (451.3/4).

Schematic diagram of heater system with labeled components A-F and coolant flow paths in orange and blue.

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See all Powertrain figures for the Fortwo (450), or browse the full figure library. Part numbers and callouts are community-sourced and cross-referenced against the manuals — confirm with your VIN before ordering.