Detecting PIM in a downstream signal, wherein the downstream signal is received from a cable plant via a subscriber network and an upstream signal is transmitted to the cable plant via the subscriber network. The upstream signal is transmitted in bursts during active intervals. PIM arises from an interaction between the upstream signal and a nonlinear component in the subscriber network and occurs in bursts corresponding to the upstream signal. The detection steps are: (a) identifying the potentially affected downstream signal from the upstream signal; (b) receiving the downstream signal during an active interval; (c) measuring a metric of the downstream signal to obtain an active value; (d) receiving the downstream signal during a quiet interval; (e) measuring the metric of the downstream signal to obtain a quiet value; (f) comparing active and quiet values; and (g) determining whether PIM distortion has been detected based on the comparison.