What Causes the Engine Fault Light to Illuminate Yellow?

[Anne]

The illumination of the yellow engine fault light is a warning, indicating that certain system parameters of the vehicle may have exceeded the set range. At this time, the vehicle can continue to drive, but some functions may be restricted. The engine fault light can also be red. When the red fault light illuminates, it means the vehicle must stop immediately, turn off the engine, and prohibit further driving while checking for the fault. There are mainly seven reasons for the engine fault 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 vehicle's ECU cannot accurately obtain engine data, causing the engine fault light to illuminate. Fuel or oil quality issues: If fuel or engine oil is not added as required by the manufacturer, it may cause engine wear, leading to the fault light illuminating. Poor mixture combustion: Poor mixture combustion can cause engine carbon buildup or knocking. When detected by the oxygen sensor and reported to the ECU, the fault light will illuminate as a warning. Spark plug failure, ignition coil failure, fuel pump failure, or fuel line blockage can all cause poor mixture combustion. Turbocharging issues: The intake turbocharging pipeline or turbocharger can also cause the engine fault light to illuminate. The most common issue is turbocharger damage, accompanied by symptoms such as oil leaks, high oil consumption, reduced power, metallic noises, or blue/black smoke from the exhaust. Intake issues: If there are problems with the vehicle's intake, it may lead to engine pipeline blockage, and in severe cases, the engine fault light will illuminate. A dirty air filter that is not cleaned regularly can cause intake problems. Exhaust issues: Exhaust faults can also cause the engine fault light to illuminate. The rear oxygen sensor, catalytic converter, exhaust camshaft, and bearing failures are common causes of exhaust problems, with the catalytic converter being the most frequent. Using leaded gasoline, lead or silicon-based lubricant additives, physical damage to the catalytic converter, or fuel supply system faults can easily cause catalytic converter issues. 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 the engine fault light will illuminate. If the engine fault light illuminates, follow these steps: First, check if the engine is running normally and if there are any issues such as shaking or smoke. If so, avoid restarting the engine. Note: Do not restart the engine if the red light is on. If the engine can start, 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 vehicle will perform a self-check after powering on. Wait for 5-10 seconds and observe if the fault light on the dashboard turns off. If the fault light remains on, visit a service center as soon as possible. The service center can use a portable diagnostic tool to read the fault code, obtain fault information, and perform targeted repairs.