A valve assembly, comprising: a pneumatically actuated valve, including: a body defining a chamber, a first fluid port coupled to the chamber, and a second fluid port coupled to the chamber; a movable stem disposed at least partially within the chamber, the movable stem having a closed position and an open position relative to the chamber, the closed position preventing fluid flow of a CO 2 working fluid between the first fluid port and the second fluid port, and the open position allowing fluid flow of the CO 2 working fluid between the first fluid port and the second fluid port; a pneumatic actuator configured to move the movable stem and operate the pneumatically actuated valve; a bonnet interposed between the body and the pneumatic actuator, the bonnet including a leak test port; and a sensor module attached to the pneumatic actuator, the sensor module including: a microcontroller, and a first sensor coupled to the microcontroller and located proximate to the leak port, the first sensor configured to provide a signal associated with a status of the pneumatically actuated valve based on a detected temperature of the CO2 working fluid detected by the first sensor, wherein the microcontroller is configured to detect a leak of the CO2 working fluid based on a change of the temperature of the CO2 working fluid detected by the first sensor. a pneumatically actuated valve, including: a body defining a chamber, a first fluid port coupled to the chamber, and a second fluid port coupled to the chamber; a movable stem disposed at least partially within the chamber, the movable stem having a closed position and an open position relative to the chamber, the closed position preventing fluid flow of a CO 2 working fluid between the first fluid port and the second fluid port, and the open position allowing fluid flow of the CO 2 working fluid between the first fluid port and the second fluid port; a pneumatic actuator configured to move the movable stem and operate the pneumatically actuated valve; a body defining a chamber, a first fluid port coupled to the chamber, and a second fluid port coupled to the chamber; a movable stem disposed at least partially within the chamber, the movable stem having a closed position and an open position relative to the chamber, the closed position preventing fluid flow of a CO 2 working fluid between the first fluid port and the second fluid port, and the open position allowing fluid flow of the CO 2 working fluid between the first fluid port and the second fluid port; a pneumatic actuator configured to move the movable stem and operate the pneumatically actuated valve; a bonnet interposed between the body and the pneumatic actuator, the bonnet including a leak test port; and a sensor module attached to the pneumatic actuator, the sensor module including: a microcontroller, and a first sensor coupled to the microcontroller and located proximate to the leak port, the first sensor configured to provide a signal associated with a status of the pneumatically actuated valve based on a detected temperature of the CO2 working fluid detected by the first sensor, a microcontroller, and a first sensor coupled to the microcontroller and located proximate to the leak port, the first sensor configured to provide a signal associated with a status of the pneumatically actuated valve based on a detected temperature of the CO2 working fluid detected by the first sensor,