How to Test an Oscilloscope Probe With a Multimeter

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The person typing how to test an oscilloscope probe with a multimeter wants a quick way to tell whether a probe is still in working order, usually after a drop, a bent tip or a reading that looks wrong. A multimeter can check the probe’s resistance from tip to ground while the probe is disconnected from the scope. Tektronix gives the typical figures to compare with: about 1 MΩ for a 1X probe and about 10 MΩ for a 10X probe. This guide sets out the check, its limits, and the ground-lead checks that matter more than the resistance number.

Quick answer

• Disconnect the probe from the oscilloscope first, and keep the probe away from any live circuit.
• Set the multimeter to resistance and measure between the probe tip and the ground clip.
• Tektronix says 1X probes typically have about 1 MΩ and 10X probes about 10 MΩ. A reading far from the figure for your probe’s setting suggests a fault to investigate.
• Check the ground lead for a break, and use the shortest ground lead the probe ships with.

Electrical safety first

An oscilloscope probe is a test lead for a circuit that may be dangerous. Do not test a probe while its tip is touching a live circuit. Remove the tip from the circuit before you disconnect the ground clip, so the ground clip is the last connection to come off. Tektronix gives this order: “When disconnecting probes from the circuit under test, remove the probe tip from the circuit first, then disconnect the ground lead.”

Tektronix also says that the ground lead is for earth ground only. The probe’s ground connection on the scope is part of the safety design of the instrument, so a probe ground should never be clipped to anything other than ground. The meter check described here happens with the probe off the scope and off any circuit, which keeps the test away from that risk.

Work on mains circuits can kill. If the probe is for mains or panel work, the meter’s CAT rating and the probe’s own rating must suit the circuit. This guide does not cover live-circuit probing, which belongs to a qualified technician.

What you need

• A digital multimeter with a resistance range that reads into the megaohm range. Fluke notes that the display may show the MΩ symbol for high values.
• The oscilloscope probe, with its tip, ground clip and any accessories still attached.
• The probe’s setting: 1X or 10X. Most probes have a switch or a marking on the body, and the scope’s own channel setting has to match it.
• A clean, dry bench with the scope unplugged or switched off.

If you need a meter that reads megaohms reliably, our megger meter guide explains that instrument. For a general overview of checking continuity, our continuity tester guide covers the beep and the OL display.

Step by step

1. Power down and disconnect. Switch the scope off, and take the probe’s BNC connector off the scope input. Keep the probe well away from any circuit.
2. Set the probe to 10X or 1X. Check the switch position against the figure you intend to compare with. Tektronix notes that a 10X probe attenuates the input signal by a factor of 10 and that the scope’s scaling is multiplied by 10 to compensate.
3. Set the meter to ohms. Plug the black lead into COM and the red lead into the VΩ jack. Turn the dial to resistance. Fluke notes that the resistance position often shares the dial with continuity, capacitance and diode tests, so check the display.
4. Check the meter with the leads open. Fluke says the display should show OL before the leads touch anything.
5. Measure tip to ground. Touch one probe lead to the probe tip and the other to the ground clip. Hold the probes by their insulated bodies, not the metal ends. Fluke says body contact with the metal ends adds a parallel path and lowers the reading.
6. Read the number. Note the reading with its unit. Compare it with about 1 MΩ for a 1X setting or about 10 MΩ for a 10X setting, using the Tektronix figures.
7. Flex the ground lead and the tip. With the meter still on the probe, gently bend the ground lead and the tip wire at several points and watch for the reading to jump or drop. A changing reading while you flex points to a fault in the lead, the connector or the tip.
8. Inspect the parts. Look at the tip, the tip’s spring, the ground clip and the BNC connector for cracks, bent parts or loose contacts. Tektronix says all accessible metal on the probe, including the ground clip, is connected to the connector shell, so a damaged clip or shell affects the ground path.

How to read the result

Tektronix’s primer explains the figures that the reading is compared against. It says that 1X probes typically have a resistance of 1 MΩ, and 10X probes typically have a resistance of 10 MΩ. It also says that these values result in negligible resistive loading for most cases. The application note adds that most 10X passive probes that ship with an oscilloscope have 10 MΩ input resistance.

Use the reading in three steps:

• Close to the figure for the setting: the resistive path is normal. This is a sanity check only. The probe may still have a fault in its capacitance or its bandwidth, which a resistance meter cannot show.
• Far from the figure: the probe, the ground lead or the connection may be damaged. Check the connections again, flex the lead, and compare with a known good probe if you have one.
• Open or zero: an open reading suggests a break in the probe lead or the tip. A zero reading suggests a short. In either case, do not use the probe on a circuit until it has been repaired or replaced.

The Tektronix primer also notes that a probe, even a simple wire, is a circuit made of resistance, inductance and capacitance. For DC signals, the probe looks like a conductor pair with some series resistance and a terminating resistance. That is why a meter on DC can show the probe’s resistance, but cannot show its behaviour at high frequency.

Ground lead and ringing

The ground lead causes more trouble than the resistance figure. Tektronix says that the ground lead is a wire with some amount of distributed inductance, and that this inductance interacts with the probe capacitance to cause ringing at a frequency set by the L and C values. It says ringing is unavoidable, but can be reduced by good probe grounding, and it advises: “To avoid grounding problems, always use the shortest ground lead provided with the probe.” Substituting other means of grounding can cause ringing to appear on measured pulses.

A long ground lead therefore changes the picture on a fast edge even when the meter reads a normal resistance. A meter check cannot show ringing. Keep the shortest ground lead the probe came with, and test the probe with that lead attached.

Compensation and matching

Tektronix says that many attenuating probes, including 10X probes, have built-in compensation networks, and that most probes are designed to match the inputs of specific oscilloscope models. Compensation is a separate matter from resistance. A multimeter reading will not show whether the compensation is off, so follow the probe maker’s manual for any compensation adjustment after a repair.

A 1X and 10X mismatch changes the scale of the picture by a factor of 10. Check that the probe switch and the scope channel setting match before you judge a reading.

Mistakes to avoid

1. Measuring a probe still on a live circuit. Remove the tip from the circuit before any check.
2. Disconnecting the ground clip first. Tektronix’s order is the tip first, then the ground lead.
3. Clipping the ground to anything but ground. Tektronix says probe ground leads connect to earth ground only.
4. Judging the probe by resistance alone. Resistance does not show capacitance, bandwidth or ringing.
5. Using a long ground lead. Use the shortest lead that ships with the probe.
6. Mismatching the probe and the channel. A 10X probe on a 1X setting shows amplitudes off by a factor of 10.

When to stop and get help

Stop and replace the probe if the lead is cut, the connector is cracked, or the tip is broken. A probe that reads wrong after a fall should not be used for measurements until it has been checked against a known good probe. For a probe that has to meet a specific bandwidth or voltage rating, use the maker’s own specification for that exact model, because the sources we opened describe classes of probe, not a single rating.

How we chose

We chose the steps in this guide by asking whether a major test-equipment maker states them in plain words. We opened two Tektronix documents: the ABCs of Probes Primer, which covers probe loading, ground leads, compensation and the typical 1X and 10X resistances, and the application note on how probes affect a measurement, which covers the input resistance and capacitance of passive probes. We also opened the Fluke resistance guide for the general meter steps: power-off measurement, the OL display, body contact and the relative mode. We did not use retail listings, forums or video clips to set any step.

What we could not verify

The sources we opened do not describe a multimeter check of a probe’s tip-to-ground resistance with an acceptance limit. The figures given are typical values, not a pass or fail rule for any model, so this guide gives no tolerance for a pass result. They do not say what a continuity reading between the probe tip and the connector centre conductor should be, so this guide does not give one. They do not say how a meter reading relates to the scope’s own input resistance. For a limit, use the probe maker’s specification for your model.

FAQ

Can I check a probe with the scope turned on?

Switch the scope off and disconnect the probe first. The meter check is made with the probe off the scope and off any circuit.

What resistance should a 10X probe show?

Tektronix gives about 10 MΩ as the typical resistance of a 10X probe. Check your model’s specification, because the sources we opened do not give a limit for a pass.

What does an open reading mean?

Fluke says OL means the leads are open or the path is broken. On a probe, it suggests a break in the lead or the tip, so the probe should not be used until it is checked.

Does the ground lead matter for a resistance check?

Yes, because the ground clip is part of the path you measure. Flex the lead and check the connection. The ground lead also matters for ringing, which a meter cannot show.

Can a multimeter check a probe’s bandwidth?

No. A meter reads resistance at a low test level. Bandwidth and capacitance need a scope-based check or the maker’s specification.

Bottom line

Disconnect the probe, measure tip to ground with the meter on resistance, and compare the reading with the typical figure for the probe’s setting. Then check the ground lead, because a normal number does not prove the probe is fit for fast signals.

Sources

• https://www.tek.com/en/documents/whitepaper/abcs-probes-primer (Tektronix, ABCs of Probes Primer; opened 2026-10-27)
• https://www.tek.com/en/documents/application-note/how-oscilloscope-probes-affect-your-measurement (Tektronix, How Oscilloscope Probes Affect Your Measurement; opened 2026-10-27)
• https://www.fluke.com/en-us/learn/blog/digital-multimeters/how-to-measure-resistance (Fluke, How to Measure Resistance with a Digital Multimeter; opened 2026-10-27)