Abstract: A device stores a vehicle identification code that includes a character string of a plurality of digits. The device includes a writing request detection section that detects a request for writing the vehicle identification code. An encoding section compresses and encodes the vehicle identification code that corresponds to the detected writing request to generate a storage code. A storage code storing section stores the storage code. Therefore, the device efficiently stores the vehicle identification codes in a nonvolatile memory.

Abstract: A device stores a vehicle identification code that includes a character string of a plurality of digits. The device includes a writing request detection section that detects a request for writing the vehicle identification code. An encoding section compresses and encodes the vehicle identification code that corresponds to the detected writing request to generate a storage code. A storage code storing section stores the storage code. Therefore, the device efficiently stores the vehicle identification codes in a nonvolatile memory.

Abstract: An apparatus and method for controlling the energization of a plurality of sensors used for detecting the air-fuel ratio in an internal combustion engine. The engine has an exhaust passage, and the air-fuel ratio sensors are provided in the exhaust passage. Each sensor includes an element for outputting a signal corresponding an oxygen concentration of the exhaust gas from the engine and a heater for heating the element. The element is activated at a predetermined temperature. A Central Processing Unit (CPU) controls the energizing the heaters. The CPU starts energizing each heater at different time. Alternatively, the CPU inputs duty signals having different phases to the heaters. As a result, the total current load from the heaters is lowered.

Abstract: A malfunction detecting apparatus detects malfunctions in an air-fuel ratio sensor employed in an internal combustion engine. The air-fuel ratio sensor is located in an exhaust passage. The output current value of the sensor varies in accordance with an applied voltage and the concentration of oxygen in the exhaust gas. An electronic control unit controls the amount of fuel in the mixture in accordance with the magnitude of the output current of the sensor such that the air-fuel ratio of the mixture is made to coincide with a target air-fuel ratio. The sensor has an applied voltage range in which the output current value remains substantially zero when the air-fuel ratio of the mixture matches a theoretical optimum air-fuel ratio.