Abstract: A heat exchanger assembly includes a coated core and an electronic coating wear sensor assembly mounted adjacent to the coated core for monitoring depletion of a coating layer of the core. The coating wear sensor assembly is electrically insulated from the coated core to ensure that an electric circuit of the coating wear sensor assembly does not affect deterioration of the core. The sensor assembly has a pair of spaced electrodes electrically insulated from each other by an insulating spacer forming a coating sample area coated with a sample layer of the coating material that provides conductive bridge between the electrodes. The coating sample area is coated with the same coating composition of the same thickness as the heat exchanger core in order to replicate the same rate coating degradation. The coating wear sensor assembly is connected to a sensing circuit that outputs to a coating condition diagnostic unit.