An unwanted portion of the total electrical [[conductivity]] [[signal]] sent to the surface from downhole [[induction log|induction logging]] instruments. The diode error is produced by the measure circuit electronics of the induction [[cartridge]]. It is isolated and measured during the [[calibration]] operation at a step where the [[sonde]] output is zero. Once evaluated, it is cancelled during the [[survey]] operation. See also [[sonde error]].