What are the reasons for the engine warning light staying on for a long time?

[CeciliaFitz]

The engine warning light may illuminate 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, triggering the engine warning 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 warning light. Poor combustion of air-fuel mixture: Poor combustion can lead to engine carbon deposits or knocking. When 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, and fuel line blockage can all cause poor combustion of the air-fuel mixture. Turbocharging issues: The intake turbocharging pipeline and turbocharger can also trigger the engine warning light. The most common issue is turbocharger damage, accompanied by symptoms such as oil leakage, high oil consumption, reduced power, metal 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 blockage, and in severe cases, trigger the engine warning light. A dirty air filter that is not cleaned regularly can cause intake problems. Exhaust issues: Exhaust system faults can also trigger the engine warning light. Common causes include rear oxygen sensor failure, catalytic converter failure, exhaust camshaft and bearing failure, 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 fuel system malfunctions can easily cause catalytic converter failure. Anti-theft system malfunction: If the vehicle's electronic anti-theft system fails 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 warning light. If the engine warning light is on, follow these steps: First, check if the engine is running normally, whether there is shaking, smoke, etc. If so, avoid restarting the engine. Especially note that if the light is red, do not restart the engine under any circumstances. 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 after powering on. Wait 5-10 seconds to see if the warning light turns off. If the warning light remains on, visit a service station as soon as possible. The service station can use a portable diagnostic tool to read the fault code, identify the issue, and perform targeted repairs.