Any complex dynamic system's ability to function successfully depends in significant part on the accuracy of the sensor data; hence sensor data validation is crucial. Because sensor data is utilized for monitoring and oversight, erroneous sensor data would result in overall poor process output. In this study, the data confidence of the sensor data is ascertained using a Mamdani fuzzy inference system. Erroneous data can be corrected with this method. If the sensor outputs faulty value for a prolonged period of time, the system will be reported and a report will be generated. This can be used as a generic module for any system. This fuzzy system is then used on the readings from an ultrasonic sensor and is used as a part of a bigger and more complex IoT system.