There is disclosed a method for diagnosing slow EGR response in an internal combustion engine equipped with an electronic controller with memory. In one embodiment, the method includes passing an EGR setpoint value and an actual EGR value through first order filters to eliminate high frequency noise; determining an actual EGR gradient as a function of any difference between the EGR set point and the actual EGR value while simultaneously determining an actual EGR gradient; and logging a fault in the electronic controller if the expected EGR gradient is greater than the actual EGR gradient by a predetermined amount.