Front Engine Coolant Reservoir Radiator Expansion Tank for Sonic 2012-2019 About this item ?OE#?603-386.?Replace OE#?42609220, GM3014167, 13502353, 95048411,603386. Package Included: 1 coolant reservoir + 1 surge cap. (Notice: instruction is not included. Recommended you install under the guidance of professionals.) ?Function? The coolant tank contains coolant fluid that is discharged from the cooling system attached to the engine. Pressure builds up and released when the coolant is hot and expanding through the radiator and when the engine cools down, the excess fluid flows back into the radiator from the coolant tank of your vehicle. If you are experiencing leaks, low level of coolant and overheating engine then you may have a problem with your coolant reservoir tank. ?Compatible with? For 2012-2016 Chevrolet Sonic (submodel:LS Hatchback,LTZ Hatchback,LTZ Sedan)?2012-2019 Chevrolet Sonic (submodel:LS Sedan,LT Hatchback,LT Sedan)?2013-2016 Chevrolet Sonic RS Hatchback?2017-2019 Chevrolet Sonic (submodel:Premier Hatchback,Premier Sedan). Please check the second picture to confirm coolant reservoir whether compatible with your vehicles. ?High-quality? The coolant reservoir expansion recovery tank with cap is made from high quality plastic materials can withstand excessive heat and vibration, light and durable, translucent, you can directly see the liquid level of the antifreeze inside, without opening the radiator cover. While this is not a genuine OEM part, it is a direct replacement and good value.