Per California Air Resources Board (CARB) regulations, On-board diagnostic (OBD) of vehicle powertrain systems are required to continuously monitor key powertrain components, such as the circuit discontinuity of actuators, various circuit faults of sensors, and out-of-range faults of sensors. The maturing and clearing of these continuous monitoring faults are critical to simplification of algorithm design, save of engineering cost (i.e., calibration), and reduction of warranty issues. Due to the nature of sensors (to sense different physical quantities) and actuators (to output energy in desired ways), most of OEM and supplies tend to choose different fault maturing and clearing strategy for sensors and actuators with different physics nature, such as timer-based, counter-based, and other physical-quantity-based strategies. Such choice brings substantial inconvenience and incurs large engineering cost for automotive manufacturers, because more and more sensors are replaced by smaller and smarter sensors that have different physics nature while achieving the same sensing functionality. It is, hence, desired to have a generic fault maturing and clearing strategy to commonize the handling of different sensors and actuators, to simplify the transition to a new hardware configuration, to provide fast and accurate maturing approach, and to smoothly handle smart sensors/actuators. This research proposed a generic fault maturing and clearing strategy to achieve the above objectives by utilizing unitless indices to mature and clear faults, standardizing the inputs and outputs, and improving compatibility with multiple designer-input options.