The intercooler is fitted between the turbocharger and engine, and between two turbochargers in twin-turbo systems. Be it an intercooler, the function remains the same: to lower the temperature of the compressed air that is generated by the turbocharger. Intercoolers are also employed in vehicles with superchargers. The intercooler is included in turbocharged vehicles for two reasons: the compressed air carries a lot of heat which can affect the engine parts by causing detonation in the cylinders, thereby lowering boost. The intercooler reduces the temperature of the air and protects the engine components. Secondly, compressed air when cooled becomes denser, which can, in turn, burn more fuel with it. This results in an additional increase in the power output of the engine. This article explains the various symptoms of defective intercoolers.