What Causes the Engine Fault Yellow Light to Stay On?

[RosalieAnn]

When the engine yellow fault light is on, it means a warning, indicating that some system parameters of the car may exceed the set range. At this time, the car can continue to drive, but some functions may be limited. The engine fault light can also be red. When the red fault light is on, it means prohibition. At this time, the car must stop immediately, turn off the engine, and prohibit continued driving, and check where the fault occurred. There are mainly the following 7 reasons for the engine fault light to stay on: Sensor failure: The sensors mentioned here include water temperature, crankshaft position, air flow, intake temperature, oxygen sensor, 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 fault light to come on. Oil quality issues: If fuel and engine oil are not added according to the manufacturer's requirements, it may cause engine wear and trigger the fault light. Poor combustion of the air-fuel mixture: Poor combustion of the air-fuel mixture can lead to engine carbon deposits or knocking. After being detected by the oxygen sensor and reported to the ECU, the fault light will come on as a warning. Spark plug failure, ignition coil failure, fuel pump failure, and fuel line blockage can all cause poor combustion of the engine air-fuel mixture. Turbocharging issues: The intake boost pipeline and turbocharger can also cause the engine fault light to come on. The most common is turbocharger damage, accompanied by symptoms such as oil leakage, high oil consumption, reduced power, metal noise, 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 fault light. A dirty air filter that is not cleaned regularly can lead to intake problems. Exhaust issues: Exhaust faults can also cause the engine fault light to come on. The rear oxygen sensor, three-way catalytic converter, exhaust camshaft, and bearing failure are all causes of exhaust problems, with the three-way catalytic converter being the most common. Using leaded gasoline, lead or silicon-based lubricant additives, physical damage to the three-way catalytic converter, and engine fuel supply system faults can easily cause three-way catalytic converter failure. Anti-theft system failure: If the car's electronic anti-theft system fails, or the anti-theft controller does not match the engine electronic controller, the anti-theft system can also cause the engine to malfunction and trigger the fault light. If the engine fault light is on, you can follow these steps: First, check if the engine is running normally and if there are any issues like shaking or smoke. If so, try not to restart the engine. Especially note that if the red light is on, do not restart the engine. 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 if the fault light on the dashboard turns off. If the fault light does not turn off, please 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.