Abstract
Low emission and less fuel consumption have become very important for the preservation of the global environment. On such a background, engine control systems capable of linear A/F control from rich to lean ranges have been put into practical use. Such engine control systems adopt highly responsive A/F sensors to attain the target air-fuel ratio quickly with high accuracy. We have recently developed a laminated sensor element structure in which the heater and the element are integrated in a compact size for better element temperature control and faster activation.