A bad or loose gas cap can trigger the “check engine” light in your car’s dashboard. The gas cap is an important component of your vehicle’s evaporative emissions control system, which prevents fuel vapors from escaping into the atmosphere.
If the gas cap is loose, damaged, or missing, it can allow fuel vapors to escape from the fuel tank, which can trigger the “check engine” light. This is because the fuel tank pressure sensor detects a drop in pressure, indicating a possible fuel vapor leak.
In some cases, the “check engine” light may not come on immediately after the gas cap is left loose or removed, as it may take a few drive cycles for the system to detect the issue. However, if the problem persists, it can cause other emissions-related issues and may also reduce your vehicle’s fuel efficiency. Therefore, it’s important to ensure that your gas cap is tightened properly after each refueling, and to replace it if it is damaged or worn out.