Example systems and related methods may relate to monitoring performance of an image forming operation. Namely, a system includes an image forming apparatus configured to execute an operation in response to receiving instructions to execute the operation. The system further includes an external sensor circuit that includes one or more sensors and a processor. The one or more sensors are configured to detect a status of an operational parameter of the image forming apparatus indicative of the image forming apparatus executing the operation and receive an instruction to exclude at least a portion of data used to detect the status of the operational parameter. The system further includes a host computing device. The host computing device is configured to generate a plurality of timestamps indicative of when the image forming apparatus executed the operation and a time frame when the external sensor circuit excluded data.