Replacement of AC/DC CLMP METER CM4375 and CM4376 series

Thank you very much for your continued patronage. We regret to inform you of an issue with the AC/DC CLAMP METER CM4375 and CM4376 series. When measuring at frequency of 100Hz or higher, the accuracy of the INRUSH (RMS) and PEAK current measurement does not satisfy the specifications. This phenomenon only happened to meters from certain specific production lots and we would like to replace the affected CM4375 and CM4376 series at no cost. We appreciate your kind understandings about the matter. Please refer to the following for more details.


1. Details of non-conformance

The INRUSH (RMS) and PEAK current measurement of the AC/DC CLAMP METER CM4375 and CM4376 series does not satisfy the accuracy specifications when the measurement frequency is 100Hz or higher. There is no problem for the INRUSH (RMS) and PEAK current measurement for the frequency lower than 100 Hz, including 50 Hz and 60 Hz.

2. Causes

The inappropriate component has been selected when changing the circuit design to improve the product in February, 2019. And the high frequency range of the INRUSH current was not evaluated sufficiently.

3. Affected models


CM4375, CM4375-20, CM4375-21, CM4375-30, CM4375-40

CM4376, CM4376-20, CM4376-21, CM4376-40

Affected products

Products manufactured between February 19, 2019 and December 23, 2020.

Serial number between 190232704 and 201247549 (for both CM4375 and CM4376)

Please note that there is no accuracy problem for the products below

  • Products manufactured before February 18, 2019
  • Products shipped in or after January, 2021
  • Products with the blue sticker on the box and battery case (below). These products were already repaired.

4. Replacement units

If you are in the Americas, and have an affected product, please contact Hioki USA for a replacement through the following contact form.

Once again, we sincerely apologize for inconvenience caused.