OL reading
OL means overload: the reading is too large for the range the meter is set to, so there is no number to show. On the resistance and continuity settings an open circuit reads OL.
How to read it
Fluke’s 114, 115 and 117 manual reads OL as an input too large for the selected range, Klein Tools’ MM400 manual lists OL for overload, and Extech’s EX330 manual calls it the overrange indication, for all functions. On the EX330 an open circuit on the Continuity symbol setting shows OL, as does a diode tested in reverse, or an open diode tested either way. Fluke’s 115 and 117 show OL above 2.0 V on the diode test and above 20 A on the amps setting, and on Fluke’s display a voltage overload also brings up the hazardous voltage symbol.
Some meters show a lone 1 instead: Mastech’s MAS838 gives its overrange indication as only the figure 1 on the display.
Also searched as: 0L, 1 on a multimeter display, OL on a multimeter, open loop, over limit, overload.
These pages describe what each setting, marking and reading means. They are not instructions for measuring anything. Meters differ between makers and models: the meter’s own manual says what each of its symbols means, which measurements it is rated for, and how to use it safely.
Look-alikes
OL is a reading, not a fault in the meter. A battery icon, or bAtt on Fluke’s meters, is the meter’s own battery.
Read next
- Next in Multimeter symbolsHOLD (display hold)HOLD freezes the reading on the display. H or HOLD on the screen shows that the hold is on.
- The same shape in OBD-II trouble codesP0705: Transmission range sensor circuit malfunction (PRNDL input)An OBD-II trouble code for a fault in the circuit of the transmission range sensor, which reports the gear selector’s position (P, R, N, D, L).
More multimeter symbols
The same shape elsewhere
Browse symbols drawn with letters and numbers or squares and rectangles.
Sources
- 114, 115, and 117 True-rms Multimeters: Users Manual, PN 2572573, July 2006, Rev. 1, 2/07, Fluke Corporation (copy hosted by UCL Electronic and Electrical Engineering), Display; Rotary switch positions
- MM400 Auto-Ranging Digital Multimeter: Instruction Manual, MM400 instruction manual, Klein Tools (copy hosted by UBC Earth, Ocean and Atmospheric Sciences), Electrical specifications
- Mini Multimeter with Non-Contact Voltage Detector, Model EX330: User’s Guide, EX330-EU-ENG V4.2 1/08, Extech Instruments (copy hosted by Core Electronics), General specifications; Continuity check; Diode test
- MAS838 Digital Multimeter: Operator’s Instruction Manual, MAS838 manual, Mastech (copy hosted by Akizuki Denshi), Specifications
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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