Error 40 in our professional devices means that the impedance measurement is disrupted and cannot be completed.

When this happens, check the following:

- Make sure nothing blocks the flow of low-frequency currents running from one electrode to the other.

Any kind of fabric (including nylon tights), plasters, sports tape, a thick layer of calluses can block the current.

- Make sure no smart watches are used during the measurement. These may interfere with the measurement process.

- Make sure that the skin of the inner thighs and the skin of the inner arms and upper body does not touch each other. Wear thin shorts and a t-shirt during the measurement to prevent the skin from touching, which may interfere with the measurement process.