What Does “OL” Mean on a Multimeter?

What Does “OL” Mean on a Multimeter?

What does “OL” mean on a multimeter? It is short for “open loop” and refers to the fact that there is no feedback mechanism. This term can be used in any situation where you are trying to measure an electrical signal without using a feedback circuit, which means it applies to many different types of devices.

The Meaning of “OL” Reading

The meaning of OL differs depending on the context. In most cases, however, it refers to an open loop, which means there is not enough continuity. It can also indicate an overvoltage and current reading [1]:

  1. When you test continuity and get the “OL” reading. If an open-loop test is attempted, the screen will display 1 or OL. This indicates that there is no continuity. Otherwise, there would be no way for electric current to flow from the probe to the probe;
  2. When you test voltage and get the “OL” reading on your multimeter. If the range is extremely low, the display will show 1 or OL, which means that it is out of range or overloaded. If the range is higher than the input voltage, the multimeter will display an error message. If you are finding “OL” on your digital multimeter while testing continuity or current then it means that there is not enough electrical connection between two points for electric flow to take place. In this case, either one of these conditions might be happening: You have failed to connect properly with a wire or cable; Your circuit board has some form of damage (such as shorting out). There may be oxidation in sockets where connectors meet such as battery terminals and so forth. Even though it won’t damage your multimeter nor put it at risk, you should set the dial to a higher range;
  3. When you test current and get the “OL” reading. If your multimeter is overloaded, the screen will display I or OL when it comes to measuring high-current circuits. This would be very useful if one were testing a large motor;
  4. When you test resistance and get the “OL” reading. If the component/circuit you’re going to test doesn’t have continuity, the device’s screen will display 1 or OL. As a result, it has an infinite resistance;
  5. You can also use this function in case of other tests like diode polarity check where both outputs are connected together through a resistance R. The meter detects no voltage difference between points A + B so it displays II = 0 Ω indicating that there’s an open circuit at point “B”;

The Meaning of “OL” Reading

In conclusion, depending on your application, getting an OL measurement during any electrical test would indicate that something went wrong with either continuity of the components being tested or excess current.

The Infinite Resistance as It Is Shown on Your Multimeter

When a pipe is filled with water, the level of resistance it offers tells you how much water passes through. Because a clogged pipe has greater resistance, only less water flows through.

A fully clogged pipe that doesn’t let water flow through has high resistance (that is off the charts). This is called infinite resistance [2].

The same goes for a multimeter when it measures electrical current. If the meter’s resistance is too high, it will not be able to measure any current at all and will show “OL” or an open loop. When this happens, you’ll need to reduce the resistance by either cleaning the probe tips or using a different set of probes.

If your meter still isn’t reading any current even after you’ve cleaned the tips, then there might be an issue with your circuit that you’ll need to troubleshoot. In some cases, you might need to use an external amplifier to boost the signal so that the meter can properly read it. In addition, you might be interested in making an amplifier using transistor guide.

The Infinite Resistance as It Is Shown on Your Multimeter

Difference between “OL” and “0” in Measuring Resistance

“OL” stands for an “open-loop” and means that the multimeter is unable to measure a lower resistance value than what it already has. The meter tries to display this measurement, but since there’s no way of displaying such an absurdly high number, it displays “OL” instead. This can happen when measuring very small resistances or if you put too low of a voltage into the circuit being tested.

0 is the measurement of open circuits and can be seen when there’s no connection between two points or if you don’t have any components connected to an analog input pin on a microcontroller (Arduino). It also shows up as “L” in some meters.

For example: if you connect the positive lead from one side of the battery directly to the ground with nothing else attached the device will show “OL”.

However, if you put that same circuit into a breadboard it could change based on how many resistors are inserted into the alligator clips at either end. If zero ohms were present then they’d act like wires and connect those two pins together so there wouldn’t be any connection and your meter would read “0”.

Difference between “OL” and “0” in Measuring Resistance

Check our useful articles about multimeters:


1. Is “OL” a good reading on a multimeter?

If the meter reads “OL”, the voltage you’re measuring is too high [3]. If you’re measuring low resistance, it’s possible that the meter will show “OL” because there is no way to display an absurdly high number. In this case, “0” is the better measurement to look for.

2. Does “OL” mean short circuit?

If your multimeter device shows infinite ohms or “OL”, it’s possible that the breaker has failed and tripped as a result of lower current flow. If the multimeter readings are good, there is a short circuit. It might be caused by an incorrect switch, broken wire, or faulty receptacle or breaker [4].

3. What does it mean when a capacitor reads “OL”?

If the multimeter can’t measure the amount of charge in a capacitor, it might display an “OL” or “overload” reading. If possible, use a higher range on your multimeter. This result might also indicate that the capacitor has shorted. An auto-ranging multimeter tests the lowest range first, then increase if it encounters an overload [5].

4. What does negative “OL” mean on a multimeter?

If the multimeter can’t read a negative voltage, it displays “OL”. If possible, use a lower range on your multimeter. Multimeters usually do not measure below 0 volts.

5. What does “OL” mean in ohms?

An “OL” reading in an ohms test means that there is not a complete circuit. It may be caused by the insulation breaking down or an incorrect switch, broken wire, or faulty receptacle.

6. How do I test a wire with a broken multimeter?

If the wire is broken, you will need to connect one end of the wire to a known good ground. This can be done by using an alligator clip or metal stake and attaching it to a bare spot on the chassis of the car. The other end of the wire should then be attached to one probe of the multimeter. Touching the other probe of the multimeter to any part of the circuit that is not connected to the ground will give you a false reading.

7. Do all multimeters test continuity?

The continuity function is used on the multimeter. A tone should be heard (not all multimeters have a continuity setting, but most should). This demonstrates that a little amount of current is permitted to flow without obstruction between probes (or at least a very tiny resistance) [6].

8. How do you reset a multimeter?

Resetting a digital multimeter is typically as simple as turning it off and on again. With some meters, you may need to hold down the power button for several seconds. If your meter has a rotary knob, try rotating it back to zero after resetting.

If you’re having trouble getting a good reading on your multimeter, try cleaning the probes with a wire brush or sandpaper. You can also use contact cleaner or DeoxIT to clean the probes (especially if they’ve been exposed to saltwater). Be sure to allow enough time for the meter to dry completely before using it again.

9. What are the symbols on the multimeter?

Multimeter symbols are used to display the condition of the circuit being tested. The following multimeter tests and their corresponding symbols:

Voltage symbol – V;
Current symbol – A;
Resistance icon – Ω;
Capacitance icon with the arrow pointing up towards positive side, or a diagonal line across it;
Temperature (measurement in Celsius);

10. Why does my multimeter read 1?

It’s overloaded if the multimeter reads 1 and displays “OL”. You’ll want to switch to a higher mode, such as 200kΩ or 2MΩ (megaohm) mode. There is no issue if this happens; it just means you’ll need to adjust the range control. If the multimeter indicates 0.00 or near zero, reduce the setting to 2kΩ or 200Ω [7].

11. What does the capacitor symbol mean on a multimeter?

This symbol stands for two parallel lines with an arrow pointing up. This indicates that the capacitor is being tested in the positive direction. If the arrow points down, it means that the capacitor is being tested in the negative direction.

Useful Video: How to Measure Ohms with a Multimeter


  1. https://handtoolsforfun.com/what-does-ol-mean-on-a-multimeter/
  2. https://handtoolsforfun.com/what-does-ol-mean-on-a-multimeter/
  3. https://ifixit.com/Answers/View/542448/Meter+displays+OL+in+voltage+continuity+mode+with+or+without+probes
  4. https://www.tpctraining.com/blogs/news/how-to-find-a-short-circuit-with-a-multimeter
  5. https://www.wikihow.com/Measure-Capacitance
  6. https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter/continuity
  7. https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter/measuring-resistance