It's not recommended to drive with a check engine light on as it indicates a problem with the car's engine or emission system. The duration a car can be driven with the check engine light on varies depending on the cause of the issue. In some cases, the problem may be minor, and the car can be driven for some time without any issues. However, in other cases, driving with the check engine light on can cause severe engine damage that can be costly to repair. It's best to have the car inspected and fixed as soon as possible to avoid any further damage.