One of the biggest misconceptions is that a check engine light is extremely detrimental to your vehicle. While a check engine light (CEL) can mean a pretty big problem, it could also be as simple as a loose gas cap. I know I have gotten fuel from New Jersey and afterwards my CEL would come on. All I would have to do is tighten the cap or even put it on correctly in the first place, and in two short trips the light would have cleared itself. Soooooo many times I have had a customer tow in their vehicle because of a simple issue like this. They could have saved the tow bill and driven it to the shop themselves.
When a CEL comes on, you can continue to drive but it is a smart idea to call your trusted repair shop and/or have your vehicle's trouble codes (DTC's) read with a scan tool to see what's causing the issue and the severity of said issue. That pesky little light may not mean the end of a road trip or that you're going to get a massive repair bill. As far as safety is concerned, the CEL will only ever come on for emissions related concerns, so you won't ever see the light because a wheel is about to fall off. Some cars will actually put the vehicle into a "Limp Mode" if there is an issue that will damage the engine and will only allow you to drive a certain speed usually around 45mph.
Now in the case of a flashing CEL, that is a cause for concern. A flashing CEL means that there is a major failure in the engine and it is causing damage to the catalytic converter. I have personally seen catalytic converters glow cherry red from a misfire or a poorly running engine. In the event of a flashing check engine light, it is advised to pull over and seek repair. More often than not, you will have some observable indication of a more serious issue, as a flashing CEL will be accompanied by some sort of lack of performance or drivability.
In short, if the light is on and not flashing and you have no drivability concerns, you should be able to drive your vehicle safely to your repair appointment.
Thanks and have a great day!
Chris @ ASM Auto