What are the reasons for the engine fault light in Jetta VS5 to illuminate?

[JaydenLee]

When there is a malfunction in the engine or related components, the engine fault indicator light on the car's dashboard will illuminate, serving as a preventive measure. Generally, the main reasons for the engine fault light to illuminate include the following. 1. Sensor issues: The sensors referred to here include those for coolant temperature, crankshaft position, air flow, intake air temperature, oxygen sensor, etc. When these sensors are damaged, have poor contact, or experience signal interruption, the car's ECU cannot accurately obtain engine data, leading to the illumination of the engine fault light. 2. Maintenance issues: Poor engine maintenance is the most common cause of the engine fault light illuminating. Vehicles have specific maintenance cycles, and if the owner does not adhere to these schedules, combined with poor driving habits, it will increase the burden on the engine's operation, eventually prompting the fault light to remind the owner to pay attention to the car. 3. Fuel quality issues: The fuel quality mentioned here includes both fuel and engine oil. The fuel added to a car usually has a specific grade, and engine oil can be semi-synthetic or fully synthetic. Manufacturers generally recommend which grade of fuel and type of engine oil to use. If the owner does not follow these recommendations, prolonged use can lead to engine wear. 4. Poor combustion of the air-fuel mixture: Faults in the engine's spark plugs, ignition coils, fuel pump, or clogged fuel lines can all cause poor combustion of the air-fuel mixture. Poor combustion leads to engine carbon buildup or knocking issues, which are eventually detected by the engine's oxygen sensor and reported to the ECU, naturally causing the fault light to illuminate as a warning. 5. Air intake issues: The engine requires air intake during combustion, making the air filter element crucial in this process. If the car's air filter is not clean and not regularly cleaned, it can affect the car's air intake. Over time, this can lead to clogging, and in severe cases, cause the engine fault light to illuminate.