Final answer:
The service technician must functionally test all physical components of the UST system except for the monitoring system certification, as it's not a component but the process itself.
Step-by-step explanation:
To complete the monitoring system certification, a service technician must functionally test all components of the UST system to ensure proper operation and regulatory compliance. In the scenario provided where a UST system with a double-wall tank and single-walled pressurized piping is being certified, and a positive shut off device is used for overfill protection, all components that are part of the system's operation and safety must be tested except for the monitoring system certification itself. The 'monitoring system certification' is not a physical component but the process being completed, so you would not 'test' the process as part of the process.