What Causes the Engine Malfunction Light to Illuminate While Driving?
2 Answers
There are primarily 7 reasons for the engine malfunction light to illuminate: Sensor malfunction: The sensors referred to here include those for 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, triggering the engine malfunction light. Fuel quality issues: Failure to add fuel and engine oil as required by the manufacturer may cause engine wear, leading to the illumination of the malfunction light. Poor mixture combustion: Poor mixture combustion can lead to engine carbon deposits or knocking. Once detected by the oxygen sensor and reported to the ECU, the malfunction light will illuminate as a warning. Issues such as spark plug failure, ignition coil failure, fuel pump failure, or 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 illuminate. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, high oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake issues: Problems with the vehicle's intake can lead to engine pipeline blockages, and in severe cases, trigger the engine malfunction light. A dirty air filter that is not cleaned regularly can cause intake problems. Exhaust issues: Exhaust faults can also trigger the engine malfunction light. Common causes include faults in the rear oxygen sensor, catalytic converter, exhaust camshaft, and bearings, with the catalytic converter being the most frequent issue. Using leaded gasoline, lead or silicon-based lubricant additives, physical damage to the catalytic converter, or faults in the engine fuel supply system can easily lead to catalytic converter failure. Anti-theft system malfunction: 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, also causing the engine malfunction light to illuminate. If the engine malfunction light illuminates, follow these steps: First, check if the engine is operating normally, looking for signs of shaking, black smoke, etc. If such symptoms are present, avoid restarting the engine. Especially note, do not restart the engine if the red light is on. If the engine can be started, turn it off for 5-10 minutes, then 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 upon powering up. After 5-10 seconds, 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 diagnose the issue. The service station can use a portable diagnostic tool to read the fault code, obtain fault information, and perform targeted repairs.
I remember one time when the engine warning light suddenly came on while driving home, and my heart skipped a beat. Usually, this light indicates a sensor issue, such as an oxygen sensor detecting abnormal exhaust emissions, or a faulty throttle position sensor causing the ECU to read incorrect data. Fuel-related problems like insufficient fuel pump pressure or clogged fuel injectors affecting the air-fuel mixture ratio can also trigger the light. Ignition system issues, such as worn-out spark plugs causing misfires, are also common. Emission faults like a clogged catalytic converter or low oil pressure can activate the warning as well. If the light comes on, don’t panic—pull over safely and check if the temperature and oil pressure gauges are normal. If everything seems stable, head to a repair shop to use an OBD tool to read the fault codes and pinpoint the issue accurately. Delaying repairs could lead to skyrocketing fuel consumption or severe engine damage, so I always make it a habit to inspect sensor components before long trips to prevent minor issues.
