Why does the engine fault light come on but everything seems normal on rainy days?

[KyleLynn]

Rainy days are not directly related to the engine fault light coming on. Here are the relevant explanations for the engine fault light illuminating: 1. Sensor issues: The sensors mentioned here include those for coolant temperature, crankshaft position, air flow, intake air temperature, oxygen, etc. When these sensors are damaged, have poor contact, or experience signal interruptions, the car's ECU cannot accurately obtain engine data, which can trigger the engine fault light. 2. Fuel quality issues: The fuel quality referred to here includes both gasoline and engine oil. The gasoline used in cars usually has a specific octane rating, and engine oil can be either semi-synthetic or fully synthetic. Manufacturers generally recommend which octane rating of gasoline and which type of engine oil to use. If the owner does not follow these recommendations, prolonged use can lead to engine wear, and no one can be blamed when the fault light comes on.