There is really no hard and fast answer to this question. It really all depends on what made the Emissions Light come on in the first place, and what you consider to be “safe.” Your emissions control reduces the amount of toxins that your vehicle delivers into the environment. So if you are concerned about your carbon footprint, you may consider the glowing Emissions Control Light to be very important.
Sometimes the Emissions Light can come on in conjunction with the Check Engine Light, and the car will still run properly – really, the only problem with the Emissions Light coming on is simply that the Emissions Light has come on. What you need to do is find out why it came on in the first place. There are certain things that you are going to have to watch out for:
If the car is running smoothly, and showing no problems other than the Emissions Light coming on, the problem could be with the sensor that triggers the light.
Most of the time, when an Emissions Light comes on, it is due to either a sensor or a problem with the exhaust gas recirculation valve.
It is also possible that you have a vacuum hose that has become disconnected, or has developed cracks.
So, is it safe to drive with the Emissions Control Light on? Yes, as long as it is the only light that has come on, you do not have to worry about your safety. However, you should still find out what is causing the problem, and then have it fixed. The best way to determine the cause is to have a qualified mechanic connect your vehicle’s diagnostic connector link to a code reader in order to determine what is causing the light to come on and stay on.