Electrical – Multimeter shows OL or 0.00 or 1.00. What’s wrong

I rarely use the feature but for more precise measurements it can be useful. For example if measuring a sensor I might want to make a note that the meter reads 2.984 V and it's more convenient than trying to remember the value while I write it down on a piece of paper or enter the value into a spreadsheet etc.

Sometimes too I might be in a position where it's hard to read the meter output at the same time and I can rest my little finger on the hold while positioning the probes.

Some higher end meters also have an auto-hold type feature where once the reading becomes stable they will take the measurement and hold the display. That's a feature that I find much more useful because you don't have to keep your eye on the meter at all and they will beep when the measurement is done.

First, do not ever operate that with the 20A/250V fuse in the 400mA/250V position. Any momentary mistake and you will severely damage your meter. You may have already done that, unfortunately, and damaged the shunt so that it reads very high. Unless the test leads are in the wrong position.

When you get the proper fuse to replace the one you blew, always remember to connect the meter in series with something that limits the current, and always remember to switch the positive test lead to the appropriate current position and always return it to volts/ohms when done.

Never leave the test lead in either current position when you are finished, always in volts/ohms.