What Are the Reasons for the Constant Illumination of the Car Engine Warning Light?
2 Answers
There are mainly 7 reasons for the engine warning light to illuminate: Sensor malfunction: The sensors mentioned here include coolant temperature, crankshaft position, air flow, intake temperature, oxygen sensors, etc. When these sensors are damaged, have poor contact, or signal interruption, the car's ECU cannot accurately obtain engine data, which will cause the engine warning light to illuminate. Fuel quality issues: If fuel and engine oil are not added as required by the manufacturer, it may cause engine wear and trigger the warning light. Poor combustion of the air-fuel mixture: Poor combustion of the air-fuel mixture 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 engine's air-fuel mixture. Turbocharging issues: The intake turbocharging pipeline and turbocharger can also cause the engine warning light to illuminate. The most common issue is turbocharger damage, accompanied by symptoms such as oil leakage, high oil consumption, reduced power, metallic noises, and blue or black smoke from the exhaust pipe. Intake issues: If there is a problem with the car's intake, it may cause engine pipeline blockage, and in severe cases, trigger the engine warning light. A dirty air filter that is not cleaned regularly can lead to intake problems. Exhaust issues: Exhaust faults can also cause the engine warning light to illuminate. The rear oxygen sensor, catalytic converter, exhaust camshaft, and bearing failures are all causes of exhaust problems, with the catalytic converter being the most common. Using leaded gasoline, lead or silicon-containing lubricant additives, physical damage to the catalytic converter, or fuel system faults can easily lead to catalytic converter failure. Anti-theft system malfunction: If the car's electronic anti-theft system malfunctions, or if the anti-theft controller does not match the engine electronic controller, the anti-theft system can also prevent the engine from operating normally and cause the engine warning light to illuminate. If the engine warning light is on, you can 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. Especially note that you must 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 pressing the clutch. The car will perform a self-check after powering on. Wait for 5-10 seconds and observe whether the warning light on the dashboard turns off. If the warning light does not turn off, visit a service station as soon as possible to identify the cause. The service station can use a portable diagnostic tool to read the fault code, obtain fault information, and perform targeted repairs.
I've been driving a sedan for many years, and the most annoying thing is when the engine warning light keeps coming on. Last time my car had this issue, the reason turned out to be a faulty oxygen sensor—it kept detecting incorrect gas concentrations in the exhaust pipe, making the computer think there was a problem. Another time, the spark plugs were severely worn, causing uneven ignition. I’ve also encountered a loose fuel cap, which let air in and triggered the warning. Every time the light comes on, I plug in an OBD scanner to read the error codes, which gives me a rough idea of the issue. I recommend not delaying repairs, as fuel consumption might increase or the engine could overheat, leading to bigger losses. Take it to a repair shop for diagnosis—often, replacing a part fixes it. Regular maintenance can prevent these problems.
