It’s okay relax; check engine light doesn’t mean that the engine is bad, check engine light indicates mostly a problem in the emission system in the car which affects the environment and may not affect the functionality of the vehicle, if you have check engine light on, it is important to solve it to save the environment from the harmful gases discharged from the tail pipe of the vehicle.
As far as the vehicle concerned, if check engine light is on it could be a very simple thing and it may not be something related to the enteral engine component.
If the car you are about to buy got a check engine light on, take a test drive and note any symptoms you find. Is it is sputtering? is it hesitating? is it shutting off? are there any noise from the engine? as i said it could be a very simple thing, so if the car is driving fine and is not showing any symptoms so no need to be alarmed.
You will need a scan tool to diagnose the problem, finding out what is the trouble code will help determine the reason for the check engine light, so when you are out to buy a car it is a good idea that you invest in a OBD-II scan tool, the basic scan tool is fairly cheap and very useful to have, when you find out the trouble code you can search the web for a description of the cod, there are many website that will list the codes with detailed descriptions on how to repair the issue and the estimated cost of repairs.
If you don’t have a scan tool you need to ask the dealer to scan the vehicle for you and tell you the reason for the warning light.
A loose gas cap, or loose air hose can cause check engine light to go on, also a bad oxygen sensor, also a dirty fuel injectors could be easily fixed by using an injectors cleaner additive by adding it to the gas tank and drive the vehicle for couple hundred miles.
Even though check engine light mostly indicates a minor issue that is easily repaired, be advised that in some situations especially with Chevrolet trucks and American V8 engines there is a possibility that the engine has low compression on one or more of the cylinders, so don’t always underestimate the warning light but don’t be alarmed as well, all you need to do is to investigate the problem before you jump to any conclusion.
I’ve personally experienced both scenarios, the first scenario is that someone goes to buy a car and the moment they see check engine light they get scared and run away not knowing that it may be a very easy issue to repair, on the other hand someone don’t bother with the light but comes to find out that there is a serious issue with the engine after they buy the vehicle.