What is the significance of the Malfunction Indicator Lamp (MIL) in the OBD II system?

The significance of the Malfunction Indicator Lamp (MIL) in the OBD II (On-Board Diagnostics II) system is that it indicates a problem has been detected that could affect vehicle emissions or performance. The MIL, often referred to as the "check engine" light, illuminates when the OBD II system detects a fault in one of the monitored systems, such as the engine, transmission, or emissions control system. When the MIL is illuminated, the OBD II system stores a Diagnostic Trouble Code (DTC) that identifies the specific problem. A scan tool can be used to retrieve the DTC and diagnose the cause of the problem. While the MIL may indicate a minor issue, it's important to have the vehicle inspected by a qualified technician to prevent further damage or emissions violations. The MIL is a critical warning signal that should not be ignored.