With the emergence of the Industry 4.0 concept, machine vibration monitoring and diagnostics systems based on the so-called smart vibration sensors using MEMS accelerometers become very popular on the market. Many automation companies use specifically designed for CbM industrial vibration sensors based on electronic chips with enclosed MEMS accelerometers. However, in the commercial vibration sensors datasheets very often are not provided detailed metrological parameters like frequency response in the declared frequency band. The article presents the results of research concerned to identification of frequency response of an exemplary available on market digital accelerometer dedicated to machines condition monitoring. The determined characteristics indicate that the sensor can be used for basic diagnostics of machines in accordance to the series of vibration standards ISO 10816 and ISO 20816. On the basis of the determined characteristics, it can be concluded that there are some non-linarites of the frequency response functions at the boundaries of the declared measurement band. It shows that application of that sensor to precise measurements conducted during scientific research could be limited.