A system to detect the presence of a catalyst includes an exhaust gas tube, a first temperature sensing device, a second temperature sensing device, a flow rate measurement device, and a processing device. The first temperature sensing device measures a first temperature of exhaust gas upstream of the exhaust gas tube. The second temperature sensing device measures a second temperature of the exhaust gas downstream of the exhaust gas tube. The processing device estimates an expected time delay between the measured inlet and outlet exhaust gas temperatures corresponding to a system with a catalyst present. The processing device may also determine the presence of a catalyst by comparing the measured second temperature to the measured first temperature and comparing the measured second temperature to an estimated delayed first temperature associated with the expected time delay.