EGR coolers are heat exchangers utilized in modern diesel engines to reduce exhaust gas recirculation (EGR) temperatures. Positioned between the EGR valve and the intake manifold, they lower the temperature of recirculated exhaust gases before they re-enter the combustion chamber, minimizing NOx formation. These coolers employ a core and housing assembly, typically constructed of brazed aluminum or robust plastic/metal composites, to facilitate efficient heat transfer using engine coolant. Internal fin designs maximize surface area for optimized cooling capacity, and pressure-tested construction ensures durability within the cooling system. Failures commonly manifest as coolant leaks or pressure loss, impacting emissions control performance.