an apparatus is disclosed for warning of the abnormality of an engine including a magneto generating an a . c . voltage and an ignition coil which includes a first signal generation section for generating a first signal including an electric quantity corresponding to the insulation resistance of lubricating oil , a temperature detecting section for producing temperature signal , a reference signal generation section for generating a reference signal in response to the temperature signal , an oil - shortage judging section for comparing the first signal and the reference signal to determine that the engine has a shortage of oil when the first signal is larger than the reference signal and generating a shortage signal , a control section for performing a short - circuit of a primary side of the ignition coil to produce a short - circuit current in response to the shortage signal and an oil - shortage display section for displaying the warning of the shortage of oil in response to the short - circuit current .