Common signs of a bad voltmeter include: a blank display, inconsistent or fluctuating readings, failure to power on, physical damage to probes or ports, or persistent error messages even when properly connected to a known good circuit.

OL stands for ‘Over Limit’ or ‘Over Load’. It indicates that the measured value exceeds the selected range. In resistance mode, it means the resistance is too high to measure (open circuit). In voltage mode, it means the voltage is higher than the selected range.

Inaccurate readings can be caused by: low battery, damaged probes, incorrect range selection, dirty probe contacts, internal component failure, or using AC mode for DC measurements (or vice versa). Always test on a known voltage source first to verify accuracy.

To test accuracy: 1) Check a known voltage source like a new battery. 2) Test continuity on a known good conductor (should be near 0 ohms). 3) Test resistance of a known resistor. 4) Ensure proper calibration according to manufacturer instructions. If readings are consistently off, your multimeter may need professional calibration or replacement.