What does it mean when the external request MIL light indicates a fault?
4 Answers
External request MIL light indicating a fault means there is a problem with the vehicle. The automotive fault code MIL stands for Malfunction-Indicator-Lamp, which refers to the malfunction indicator light. Solutions for MIL light fault: When the vehicle's malfunction indicator light comes on, if obvious faults in the fuel system, air intake system, or electrical system are found during engine inspection, they can be resolved by yourself. If no obvious faults are detected and normal driving is not affected, you can choose an appropriate time to visit a repair station. If the existing fault affects normal driving, you must immediately go to a repair station for maintenance and avoid attempting blind repairs on your own. Introduction to the malfunction indicator light: The malfunction indicator light is located on the instrument panel; its color is generally red (refer to the vehicle manual for specifics). The malfunction indicator light stays on for 2 seconds before turning off; it lights up when the electronic fuel injection system detects a fault; for general faults, the malfunction indicator light remains on.
When the MIL light suddenly comes on in your car, just like when I was driving that old Toyota last time, it means the engine computer has detected an issue with the emission system. It could be a dirty oxygen sensor, reduced efficiency of the catalytic converter, or even a loose fuel cap triggering this yellow light. Last time I encountered this, I specifically went to a repair shop to check the trouble codes, and it turned out to be carbon buildup in the fuel injectors causing a rich fuel mixture. I recommend not rushing to reset it by disconnecting the battery; instead, use a diagnostic tool to read the specific trouble codes as soon as possible. Otherwise, a minor issue could escalate into a major repair, costing you dearly. This kind of light usually doesn’t affect short-distance driving, but it must be addressed before long trips, as excessive emissions can also damage the engine.
Last time I drove my friend's German car, the MIL light came on, which is actually the warning light for engine emission faults. Common causes include abnormal readings from the mass airflow sensor or carbon buildup clogging the exhaust gas recirculation system. I remember one time when aging spark plugs also triggered this warning light. In such cases, I usually check if the fuel tank cap is sealed first—a small detail often overlooked. Don't fall for the online 'disconnect the battery' trick; it's better to use professional equipment to read the fault codes. The mechanic told me that over 80% of MIL light issues can be fixed within 500 RMB, but delaying repairs can lead to soaring fuel consumption or even damage the catalytic converter.
The MIL light is the yellow engine icon on the dashboard, which indicates an issue with the emission system. Common causes include a faulty oxygen sensor or reduced catalytic converter efficiency leading to excessive exhaust emissions. Once, after I cleaned the throttle body, the light went off, showing that excessive carbon buildup can also trigger it. It's advisable to check the trouble codes promptly, unlike my colleague who waited until the vehicle inspection failed to address it. The rules for the light vary by car make; for example, American cars might simultaneously illuminate the EPC light, while Japanese cars often experience idle vibration when the light is on.
