What are the reasons for the engine malfunction indicator light being on?
2 Answers
The reasons for the engine malfunction indicator light being on: 1. Sensor issues: including coolant temperature, crankshaft position, air flow, intake air temperature, oxygen sensors, etc. When these sensors are damaged, have poor contact, or signal interruption, the car's ECU cannot accurately obtain engine data, which will cause the engine malfunction light to illuminate; 2. Maintenance issues: Poor engine maintenance is a common cause of the engine malfunction light coming on; 3. Fuel quality issues: Manufacturers generally recommend which grade of fuel and type of engine oil to use. If the owner does not follow these recommendations, long-term use will cause engine wear, and the malfunction light will illuminate; 4. Poor combustion of the air-fuel mixture: Engine spark plug failure, ignition coil failure, fuel pump failure, fuel line blockage, etc., can all lead to poor combustion of the air-fuel mixture. Poor combustion results in engine carbon deposits or knocking issues, which are eventually detected by the engine's oxygen sensor and reported to the ECU, naturally triggering the malfunction light as a warning.
The engine warning light is quite a common issue. I've encountered it several times in my ten years of driving. When the light comes on, it usually indicates a problem with the vehicle's emission control system, such as a faulty exhaust sensor or a clogged catalytic converter, which triggers an alarm when it detects substandard exhaust emissions. Other possible causes include unstable fuel injection from the injectors, aging ignition systems like worn-out spark plugs, or even a loose fuel cap causing a leak signal. Checking it is straightforward—just take it to a repair shop and plug in a diagnostic tool to read the fault code. Don't ignore this light, as it can lead to a significant increase in fuel consumption, and in severe cases, even cause the engine to stall unexpectedly, causing inconvenience. Regular maintenance, including checking sensor cleanliness and connector connections, can help prevent such issues.
