What Could Be the Reason for the Malfunction Indicator Light Staying On While the Car Runs Normally?

[OGavin]

It could be due to a damaged sensor. Reason: If the sensor is damaged, it may transmit incorrect signals, which can also trigger the malfunction indicator light. If this is the cause, simply replacing the sensor should resolve the issue. If the sensor is confirmed to be functioning properly, the cause of the exhaust emission problem is mostly due to carbon buildup, and the vehicle's carbon buildup may be quite severe. Precautions: This is related to both usual driving habits and the type of fuel used. If unsuitable or poor-quality gasoline is used, it may not burn completely, leading to carbon buildup.