What causes the engine warning light to sometimes come on and sometimes go off?

[JaydenLee]

Engine warning light flashing indicates that there is a problem with the engine, and the issue is relatively serious, requiring immediate inspection. The specific reasons may include the following 7 possibilities: Sensor malfunction: The sensors mentioned 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, which will trigger the engine warning light. Fuel or oil quality issues: If fuel or engine oil is not added according to the manufacturer's requirements, it may cause engine wear and trigger the warning light. Poor combustion of the air-fuel mixture: Poor combustion can lead to engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the warning light will illuminate as a warning. Faulty spark plugs, ignition coils, fuel pumps, or clogged fuel lines can all cause poor combustion of the air-fuel mixture. Turbocharging issues: Problems with the intake boost pipes or turbocharger can also trigger the engine warning light. The most common issue is a damaged turbocharger, accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake issues: If there is a problem with the car's air intake, it may lead to clogged engine pipes, 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 malfunctions can also trigger the engine warning light. Common causes include faulty rear oxygen sensors, catalytic converters, exhaust camshafts, or 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 fuel system malfunctions can all 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's electronic controller, the anti-theft system can prevent the engine from operating normally and trigger the engine warning light. Generally, the engine warning light can appear in four scenarios: steady yellow light, flashing yellow light, steady red light, or flashing red light. The severity of the issue increases from steady to flashing and from yellow to red. In order of severity: flashing red > flashing yellow/red > steady red > steady yellow/red. If the engine warning light comes on, follow these steps: First, check if the engine is running normally, whether there is shaking, black smoke, etc. If so, avoid restarting the engine. 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 pressing the clutch). The car will perform a self-check after powering on. Wait 5-10 seconds and observe whether the warning light on the dashboard turns off. If the warning light remains on, visit a service center as soon as possible. The service center can use a portable diagnostic tool to read the error codes, identify the issue, and perform targeted repairs.