Some of the signals in automotive electronics change at very fast rates, up to a thousandth of a second, and usually the scanning speed of the test instrument should be 5 to 10 times the measured signal.Many fault signals are intermittent, sometimes no, which requires the instrument to test faster than the speed of fault signals. Digital oscilloscope can meet this speed requirement. It can not only quickly capture circuit signals, but also display these waveforms at a slower speed, so that maintenance personnel can observe and analyze at the same time. It can also record the signal waveform in a stored way, and can rewind to observe the fast signal that has happened, which provides great convenience for analyzing the fault. Whether it is a high speed signal (e.g., fuel injector signal) or a low speed signal (e.g., throttle position change and oxygen sensor signal), an oscilloscope can be used to observe the waveform to find clues. An oscilloscope is like a ruler. It can measure the working conditions of the computer system.