Engine fault lights come in two colors: yellow and red. When the yellow fault light is on, you can continue driving; when the red fault light is on, you must stop driving immediately. When the yellow fault light is illuminated, it serves as a warning, indicating that certain system parameters in the car may have exceeded the set range. The vehicle can still be driven, but some functions may be limited. When the red fault light is on, it indicates a serious fault, and the car must be stopped immediately. Turn off the engine, refrain from further driving, and check for the source of the fault. There are seven main reasons why the engine fault light may come on: Sensor malfunction: Sensors such as coolant temperature, crankshaft position, air flow, intake temperature, and oxygen sensors may become damaged, have poor contact, or lose signal. When the car's ECU cannot accurately obtain engine data, the engine fault light will illuminate. Fuel or oil quality issues: If fuel or engine oil is not added according to the manufacturer's requirements, it may cause engine wear, leading to the fault light turning on. 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 fault light will illuminate as a warning. Issues such as faulty spark plugs, ignition coils, fuel pumps, or clogged fuel lines can cause poor combustion. Turbocharger problems: Issues with the intake boost pipes or turbocharger can also trigger the engine fault light. The most common problem is a damaged turbocharger, often accompanied by symptoms such as oil leaks, excessive oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake problems: If the car's air intake is compromised, it may lead to engine pipe blockages, which can trigger the fault light. A dirty air filter or lack of regular cleaning can cause intake issues. Exhaust problems: Exhaust system faults can also cause the engine fault light to illuminate. Common causes include faulty rear oxygen sensors, catalytic converters, exhaust camshafts, or bearings. The catalytic converter is the most frequent issue, often due to the use of leaded gasoline, lead- or silicon-containing oil additives, physical damage, or fuel system malfunctions. Anti-theft system malfunction: If the car's electronic anti-theft system fails or the anti-theft controller does not match the engine ECU, the engine may not function properly, and the fault light will turn on. If the engine fault light comes on, follow these steps: First, check whether the engine is running normally. If there are issues such as shaking or smoke, avoid restarting the engine. Note: If the red light is on, do not restart the engine under any circumstances. If the engine can be started, turn it off and wait 5-10 minutes. 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, and after 5-10 seconds, check whether the fault light has turned off. If the fault light remains on, visit a service center as soon as possible. Technicians can use a diagnostic tool to read the fault code, identify the issue, and perform targeted repairs.
