What causes the engine malfunction indicator light to come on?
2 Answers
The reasons why the engine malfunction indicator light comes on: 1. Sensor issues: When a sensor is damaged, has poor contact, or experiences signal interruption, the car's ECU cannot accurately obtain engine data, which will then trigger the engine malfunction light; 2. Intake problems: If the car's air filter is not clean and not regularly cleaned, it can affect the car's air intake. Over time, this can lead to blockage, and in severe cases, it will cause the engine malfunction light to come on; 3. Poor combustion of the air-fuel mixture: Poor combustion of the air-fuel mixture leads to engine carbon deposits or knocking issues, which are detected by the engine's oxygen sensor. After reporting to the ECU, the malfunction light will naturally come on as a warning.
Having driven for twenty years, I've seen too many cases of the engine light coming on. The most common issue is sensors acting up, like the oxygen sensor detecting something wrong with the exhaust and triggering an alarm—fixing this isn’t too expensive. If the car is noticeably shaking and lacking power, it’s likely due to bad spark plugs or a faulty ignition coil. I’ve also seen friends who tried to save money by filling up at small gas stations, only for the engine light to immediately give them trouble. Simple oversights like a loose gas cap have happened to me three times. But the worst scenarios involve core components, such as a clogged catalytic converter or a misaligned timing chain—those can cost a fortune. Never ignore the engine light; the safest move is to read the trouble codes right away. Just yesterday, I helped a neighbor use an OBD scanner to diagnose carbon buildup in the throttle body as the culprit.
