A kit for retrofitting an oven processing system can be used to upgrade temperature monitoring capability. The oven processing system includes an oven and a conveyor belt. The oven defines a heated tunnel. The conveyor belt travels through the tunnel along a lateral axis. The kit at least includes a plurality of sensor modules. The sensor modules are elongate bodies with a sensing end that is mounted inside the oven. The sensor modules individually include a gas conduit and an electrical cable. The gas conduit is coupled to a pressurized source of gas. The electrical cable is coupled to a data acquisition unit that is located outside of the heated tunnel.