The present disclosure includes a system and method for regulating exhaust gas recirculation (“EGR”) in an engine. In one embodiment, the system may include a knock sensor coupled to the engine that sends a signal corresponding to at least one operating condition of the engine to a controller. The controller may estimate an amount of EGR gas administered to the engine and regulate the amount of EGR gas being administered to the engine when the estimated amount of EGR gas is not an effective amount.