A method of monitoring performance of a fluid testing system is provided. The method draws a fluid sample to the testing system using a pump. A voltage output of a sensor, such as an optical sensor, is generated. The voltage output of the optical sensor during the drawing is compared to an upper fluid volume drawn based voltage limit and a lower fluid volume drawn based voltage limit stored within a memory. The system is flushed with a flushing fluid using the pump to flush the flushing fluid from the testing system. The voltage output of the optical sensor during the flushing is compared to an upper fluid volume flushed based voltage limit and a lower fluid volume flushed based voltage limit stored within the memory. An alert generates if at least one of the voltage output during the drawing of the fluid sample is outside of voltage limits.
