Techniques for monitoring health of an igniter (202) in a gas turbine engine (201) include a sensor (270) mounted to detect signals in a combustor (260) and a processor (180) in electrical communication with the sensor. The processor is configured to receive (601) from the sensor first data that indicates signal changes in each of a plurality of time bins during operation of the igniter in the combustor. Information characteristics of the first data are determined (603). A value is determined (615) of a similarity measure that indicates similarity of the information characteristics to target information characteristics. Based on the value of the similarity measure, a condition of the igniter is determined (633) and a device is operated (635) based on the conditions, for example the condition is presented on a display (714).