Why Does the Engine Malfunction Light Come On?
2 Answers
There are mainly 7 reasons why the engine malfunction light comes on: 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 will cause the engine malfunction light to come on. Fuel quality issues: If fuel and engine oil are not added as required by the manufacturer, it may cause engine wear and trigger the malfunction light. Poor mixture combustion: Poor mixture combustion can lead to engine carbon deposits 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 mixture combustion in the engine. 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 pipe. Intake issues: If the vehicle's intake system has problems, 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 issues. Exhaust issues: Exhaust system failures can also cause the engine malfunction light to come on. Rear oxygen sensor failure, catalytic converter failure, exhaust camshaft and bearing failure 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 the anti-theft controller does not match the engine electronic controller, the anti-theft system can also cause the engine to malfunction and trigger the engine 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 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 for 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 enter self-check mode after powering on. Wait for 5-10 seconds and observe whether the malfunction light on the dashboard turns off. If the malfunction light remains on, visit a service center as soon as possible. The service center can use a portable diagnostic tool to read the fault codes, obtain fault information, and perform targeted repairs.
A few days ago, while driving home, I suddenly noticed the engine warning light on the dashboard was illuminated. To be honest, it was quite alarming since the light could indicate serious engine issues. The most common cause is a faulty oxygen sensor, which monitors exhaust oxygen levels—if the readings are inaccurate, the light will come on. Other scenarios like worn spark plugs or ignition coil failures can also trigger the light due to incomplete combustion from a malfunctioning ignition system. Fuel system problems, such as clogged fuel injectors or a loose gas cap, may also trigger the warning. I once had the light come on just because the gas cap wasn’t tightened properly, and a quick check fixed it. Vacuum leaks or aged hoses around the engine allowing abnormal air intake can also cause the control unit to send false signals. My advice: don’t delay—visit a reputable repair shop promptly to read the trouble codes with a diagnostic tool and address the issue accordingly to ensure driving safety.
