SYSTEMS AND METHODS FOR RUNNING A NOx SELF-DIAGNOSTIC TEST

Methods and systems are provided for detecting NOx sensor degradation based on results from a NOx sensor self-diagnostic (SD) test. In one example, a method may comprise: determining that a nitrogen oxide (NOx) sensor is degraded if outputs received from the sensor via a CAN bus during a self-diagnostic test are outside a threshold range. Additionally, only outputs received from the sensor during a self-diagnostic (SD) test performed after a first completed SD test after a key-off event, where the outputs are generated under conditions where a temperature at the sensor is less than a threshold, and an oxygen concentration is within a threshold range may be used to determine if the sensor is degraded. 本发明涉及用于进行NOx自诊断测试的系统和方法。提供了基于来自NOx传感器自诊断(SD)测试的结果检测NOx传感器劣化的方法和系统。在个示例中，方法包括：如果在自诊断测试期间经由CAN总线从传感器接收的输出在阈值范围之外，则确定氮氧化物(NOx)传感器劣化。此外，只有在钥匙关闭事件后的第完成的SD测试后所执行的自诊断(SD)测试期间从该传感器接收的输出可以被用来确定该传感器是否劣化，其中该输出是在该传感器的温度低于阈值并且氧浓度在阈值范围内的条件下产生的。