Electronic control unit

In an electronic control unit (2) having two computers (4, 6), the first computer (4), which is an engine control microcomputer, performs multiple diagnoses (S100-S130, S140-S170) and sends data regarding the diagnoses (S100-S130, S140-S170) to the second computer (6), which is a throttle control microcomputer. The data includes a transmission ID, a calculated value and a reference value. The throttle control microcomputer (6) directly monitors completion of the diagnoses (S100-S130, S140-S170) based on the data.