A cathodic protection system for a buried, fluid pipeline that has an electrical lead or coil electrically coupled between the pipeline and a sacrificial anode. As the anode deteriorates by electrochemical reaction with its environment, a current flows through the lead or coil, producing an electromagnetic field that permeates the pipeline. The strength of this magnetic field can be correlated to the condition of the sacrificial anode and/or the condition of a protective coating on the pipeline. An apparatus for detecting the strength of the electromagnetic field travels through the pipeline in a scraper or similar device, senses the magnitude of the field, and generates a signal indicative of the condition of the cathodic protection system.