PURPOSE: To enable the abnormal condition of an internal combustion engine to be effectively detected by discriminating the monitored conditions of the engine, computing a fuel consumption rate based on an injector energizing time information and storing it in a memory by write means.

CONSTITUTION: An apparatus is provided with a microprocessor (MPU) 11, an input interface 12, an A/D converter 13, a memory 14 and a controller 10 comprises a stand-by RAM 15 and an output interface 16. When an ignition switch 18 is closed, the MPU 11 decides whether or not the apparatus is in a monitoring condition based on a variety of engine parameters inputted through the input interface 12. When in the monitoring condition, the information of the energizing time of an injector 22 is obtained to be stored in the memory 14 and a fuel consumption rate is computed to be stored in the stand-by RAM 15. Thus, the abnormal condition of an internal-combustion engine can be detected with a high accuracy.