What Causes the Engine Malfunction Light to Illuminate?
3 Answers
There are primarily 7 reasons for the engine malfunction light to illuminate: Sensor failure: The sensors mentioned here include coolant temperature, crankshaft position, air flow, intake air temperature, oxygen sensors, etc. When these sensors are damaged, have poor contact, or experience signal interruption, the vehicle's ECU cannot accurately obtain engine data, which triggers the engine malfunction light. Fuel quality issues: If fuel and engine oil are not added according to the manufacturer's requirements, it may cause engine wear and lead to the malfunction light illuminating. Poor combustion of the air-fuel mixture: Poor combustion can lead to engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the malfunction light will illuminate as a warning. Spark plug failure, ignition coil failure, fuel pump failure, and fuel line blockages can all cause poor combustion of the engine's air-fuel mixture. Turbocharging issues: The intake turbocharging pipeline and turbocharger can also cause the engine malfunction light to illuminate. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, high oil consumption, reduced power, metallic noises, and blue or black smoke from the exhaust pipe. Intake issues: If the vehicle's intake system has problems, it may lead to engine pipeline blockages, and in severe cases, cause the engine malfunction light to illuminate. A dirty air filter that is not cleaned regularly can lead to intake problems. Exhaust issues: Exhaust system failures can also cause the engine malfunction light to illuminate. The rear oxygen sensor, catalytic converter, exhaust camshaft, and bearing failures are all causes of exhaust problems, with the catalytic converter being the most common. Using leaded gasoline, lead or silicon-based lubricant additives, physical damage to the catalytic converter, or engine fuel supply system failures can easily cause catalytic converter issues. Anti-theft system failure: If the vehicle's electronic anti-theft system malfunctions or if the anti-theft controller does not match the engine electronic controller, the anti-theft system can prevent the engine from operating normally and cause the malfunction light to illuminate. If the engine malfunction light is on, follow these steps: First, check if the engine is running normally and whether there are issues such as shaking or black smoke. If so, avoid restarting the engine. Note: Do not restart the engine if the red light is on. If the engine can start, turn it off and wait 5-10 minutes. Without pressing the brake, press the start button once or turn the key halfway to the "on" position without pressing the clutch. The vehicle will perform a self-check after powering on. Wait 5-10 seconds and observe whether the malfunction light on the dashboard turns off. If the malfunction light remains on, visit a service station as soon as possible to identify the cause. The service station can use a portable diagnostic tool to read the fault codes, obtain fault information, and perform targeted repairs.
When my car's engine warning light comes on, my first reaction is to check for unusual noises or vibrations. Usually, the issue lies with sensors, such as an aging oxygen sensor or carbon buildup causing inaccurate readings, which affects the emission system. It could also be worn spark plugs causing unstable ignition, a clogged fuel pump leading to insufficient fuel supply, or unstable battery voltage interfering with the ECU. Even minor issues like a loose gas cap can trigger the light, which is quite annoying. I recommend using an OBD scanner to read the trouble codes and roughly locate the problem first. Don't delay addressing it, as this could lead to engine damage or increased fuel consumption. While driving, always pay attention to the coolant temperature and oil pressure indicators. Regular maintenance, such as cleaning sensors and replacing the air filter, can significantly reduce the chances of the light coming on.
Last year, my car suddenly had a warning light come on, which scared me into pulling over to check. First, I tried replacing the spark plugs, but that didn’t fix it; then, after cleaning the mass airflow sensor, the light went off. This issue can be triggered by various factors: loose sensor wiring, a dirty or clogged fuel filter, or the ECU receiving incorrect signals. I recommend car owners keep a mobile diagnostic app handy—it’s cheap and quick, allowing you to read codes and pinpoint the problem. If the light stays on but the car runs normally, you can drive slowly to a repair shop; if it flashes or the engine shakes, stop immediately and call a tow truck. For prevention, I check the emissions system every six months and avoid using low-quality gasoline.
