The engine warning light may stay on for the following 7 main reasons: Sensor malfunction: The sensors involved include those for coolant temperature, crankshaft position, air flow, intake air temperature, oxygen, etc. When these sensors are damaged, have poor contact, or their signals are interrupted, the vehicle's ECU cannot accurately obtain engine data, triggering the engine warning light. Fuel and oil quality issues: Failure to use the fuel and oil as specified by the manufacturer may cause engine wear, leading to the illumination of the warning light. Poor combustion of the air-fuel mixture: This can result in engine carbon buildup or knocking. Once detected by the oxygen sensor and reported to the ECU, the warning light will illuminate as a warning. Spark plug failure, ignition coil failure, fuel pump failure, or fuel line blockage can all cause poor combustion of the air-fuel mixture. Turbocharging issues: Problems with the intake boost pipeline or turbocharger can also trigger the engine warning light. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake issues: If the vehicle's intake system is compromised, it may lead to engine pipeline blockages, and in severe cases, trigger the engine warning light. A dirty air filter that hasn't been cleaned regularly can cause intake problems. Exhaust issues: Exhaust system faults can also cause the engine warning light to illuminate. Common causes include faults in the rear oxygen sensor, catalytic converter, exhaust camshaft, or bearings, with the catalytic converter being the most frequent issue. The use of leaded gasoline, lead or silicon-containing lubricant additives, physical damage to the catalytic converter, or fuel system malfunctions can easily lead to catalytic converter failure. Anti-theft system malfunction: If the vehicle's electronic anti-theft system fails, or if there's a mismatch between the anti-theft controller and the engine electronic controller, the anti-theft system can prevent the engine from operating normally, also causing the engine warning light to illuminate. If the engine warning light is on, follow these steps: First, check if the engine is running normally, looking for signs of shaking, smoke, etc. If such symptoms are present, avoid restarting the engine. Particularly, 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 perform a self-check when powered on. After 5-10 seconds, observe whether the warning light on the dashboard turns off. If the warning light remains on, visit a service station as soon as possible for diagnosis. The service station can use a portable diagnostic tool to read the fault codes, identify the issue, and perform targeted repairs.
