BMW 17-11-1-437-362 E46 325i 330i Coolant Expansion Tank Thermostat&nbsp;, 1 Pack This Unit controls the temperature of your automatic transmission fluid Heat Exchanger for your automatic transmission, usually changed when you replace your Expansion tank Fits M52/M54 2.5L, 2.8L 3.0L Genuine BMW part Number: 17111437362