What does it mean when the engine malfunction indicator light comes on?
2 Answers
The engine malfunction indicator light may come on due to the following 7 main reasons: Sensor malfunction: 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 will trigger 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 trigger the malfunction light. Poor fuel mixture combustion: 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 blockage can all cause poor fuel mixture combustion. Turbocharging issues: The intake turbocharging pipeline and turbocharger can also cause the engine malfunction light to come on. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, and blue or black smoke from the exhaust. Intake issues: If there is a problem with the vehicle's intake, it may cause engine pipeline blockage, and in severe cases, trigger the engine malfunction light. A dirty air filter that is not cleaned regularly can lead to intake problems. Exhaust issues: Exhaust faults can also cause the engine malfunction light to illuminate. Common causes include rear oxygen sensor failure, three-way catalytic converter failure, exhaust camshaft and bearing failure, with the three-way catalytic converter being the most frequent issue. Using leaded gasoline, lead or silicon-based lubricant additives, physical damage to the catalytic converter, or fuel system faults can easily cause three-way catalytic converter failure. Anti-theft system malfunction: If the vehicle's electronic anti-theft system malfunctions or the anti-theft controller does not match the engine electronic controller, the anti-theft system can prevent the engine from operating normally and trigger the malfunction light. If the engine malfunction light comes 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 warning light is on. If the engine can be started, 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 depressing the clutch. The vehicle will perform a self-check after powering on. Observe whether the malfunction light turns off after 5-10 seconds. If the light remains on, visit a service center as soon as possible. The service center can use a portable diagnostic tool to read the fault code, identify the issue, and perform targeted repairs.
As a driver with over 20 years of experience, I've encountered the engine warning light multiple times and know it's often triggered by minor issues. For instance, a loose gas cap can cause false system alerts, and sensor malfunctions may also activate the warning. My approach is to stay calm, first check if the gas cap is properly tightened, then drive around for a while to see if the light turns off. If the light remains on, it might indicate emission control problems like a faulty oxygen sensor or issues with the fuel injection system. Never ignore it - I recommend visiting a repair shop to scan for trouble codes using an OBD scanner to prevent engine damage and higher repair costs from delays. While DIY solutions can save money, safety comes first - never take risks on highways.
