If the check engine indicator light up not long after you done refueling, it might be due to refilling the tank with bad quality fuel, causing incomplete oil and air mixture in the engine which lead to the check indicator light up. This will not affect driving safety but will cause the below harms to the engine:
1. Fuel with low RON rating is unstable in combustion which will cause engine knocking and valve abnormal noise. It might also damage the head cover, drive shaft, piston conrod and valve lifter if the condition is severe.
2. Fuel contain water which will condense into water column during low temperature, blocking the fuel supplying hose and affect fuel supplying. It will also lower the heat production of the fuel and worsen the combustion procedure, speed up fuel hydrolysis/oxidation causing the additive dissolve and precipitate losing its function. The fuel contain water when contacting the car metal part will cause rust easily.
3. Fuel contain mechanical impurities will clogged the fuel supplying hose and fuel filter, damage the carburetor as well as causing heavy wear to the fuel pump. If the engine check indicator light up after refueling, suggest to diagnose at workshop as soon as possible.
Suggest to diagnose at workshop, usual keypoints of diagnose are:
1. Check the carbon deposit build up condition in the engine, clean it.
2. Check the clogged condition of the fuel hose, replace if necessary.
3. Check the fuel filter and carburetor condition, replace if necessary.
4. Replace the fuel.