The AC voltages produced by most automotive magnetic sensors do not produce a true sine wave. In other words, the voltage and frequency of the signal varies. Examples of these types of sensors include ABS wheel-speed sensors and some crankshaft sensors. To get an accurate voltage reading from these types of sensors, look for a meter with true RMS sampling circuitry. A meter with averaging circuitry will display a significantly different — even erroneous — reading.
Of course, there are even more specs beyond these, but the ones outlined here represent the main “guts” of most meters. So, with due diligence and awareness of your diagnostic needs, you’ll be able to compare your way to exactly the multimeter for your specific needs.