The present disclosure relates to semiconductor tool monitoring system having multiple sensors configured to concurrently and independently monitor processing conditions of a semiconductor manufacturing tool. In some embodiments, the disclosed tool monitoring system comprises a first sensor system configured to monitor one or more processing conditions of a semiconductor manufacturing tool and to generate a first monitoring response based thereupon. A redundant, second sensor system is configured to concurrently monitor the one or more processing conditions of the manufacturing tool and to generate a second monitoring response based thereupon. A comparison element is configured to compare the first and second monitoring responses, and if the responses deviate from one another (e.g., have a deviation greater than a threshold value) to generate a warning signal. By comparing the first and second monitoring responses, errors in the sensor systems can be detected in real time, thereby preventing yield loss.