What can an oscilloscope be used for in engine diagnostics?

An oscilloscope is a versatile diagnostic tool used in engine diagnostics primarily because it can capture and display the waveforms of electrical signals over time. This ability makes it ideal for analyzing various components of an engine's ignition system.

Using an oscilloscope to read spark plug firing voltage allows technicians to visualize the voltage patterns at the spark plug during operation. By examining the waveform, they can assess whether the spark is firing correctly, identify misfires, and determine if the ignition system is providing sufficient voltage.

Similarly, checking ignition coil performance with an oscilloscope enables the technician to observe the voltage output from the coil. This can reveal issues such as weak spark production or timing problems, which are critical for optimal engine performance.

By providing detailed waveform analysis for both spark plug firing and ignition coil performance, the oscilloscope serves as a valuable tool for diagnosing engine issues. In this context, the correct answer recognizes that the oscilloscope is useful for both tasks, demonstrating its importance in engine diagnostics.