The wide interest in the development of diagnostic techniques for automotive purposes has led to developments in several areas. These include sensing methods, signal processing methods, and studies of how mechanical systems fail. This paper, concerned with only the first of these categories, presents an overview of sensors with emphasis on new developments that may be useful in the diagnostic field. Among the parameters which may be measured in automotive diagnostic systems are pressures, speeds, flow rates, temperatures, vibration, and electrical measurements. This paper will discuss various methods by which such parameters can be measured.