Need a replacement catalytic converter for your 2018 Freightliner MT55? MagnaFlow offers high-quality, OEM-Grade catalytic converters engineered for various 2018 MT55 sub-models and engine sizes, designed to keep the check engine light off. We combine efficient design and state-of-the-art manufacturing to meet or exceed required emissions standards. To find the correct catalytic converter, select your 2018 Freightliner MT55 sub-model and engine size, along with your state vehicle registration. This will ensure you purchase a converter that fits your vehicle and meets your state's emissions regulations.