What does the check engine light mean?

What does the Check Engine Light mean? Hopefully, you’re lucky enough not to have seen this particular light pop up on your dashboard. It’s an important light, one that can mean lots of different things. 

Often, issues that make this light appear are related to emissions or your fuel and exhaust system in some way. It could be as simple “as a loose gas cap or a faulty oxygen sensor or spark plug or something as severe as a faulty catalytic converter or major engine problems,” says Cars.com. Here are some things to remember:

1. The Check Engine Light coming on doesn’t always mean a breakdown is imminent – it’s often meant to be an early warning. Sometimes it is more imminent and will need attention sooner – if it’s dire, your Check Engine Light will sometimes blink rapidly instead of staying constantly lit. Always check your owner’s manual, but flashing is generally a sign of a serious issue. Read more on a blinking Check Engine Light here.
2. When your Check Engine Light is on, it stores a diagnostic code within the vehicle’s system – the code isn’t the final answer to the problem, just the place to start. The code sends you into a diagnostic process provided by the manufacturer. Sometimes it is simple, but more times than not it’s a breadcrumb.
3. Sometimes it’s emissions related – it could be as simple as a problem with your gas cap. If your gas cap is off, even that could trigger it. Every time you start your car and when you’re driving, the system is going through a series of self-checks and different types of driving (how far, how fast, etc) can trigger different self-checks.
4. Usually, Check Engine Light items are all related. Sometimes a failure in one piece can cause failure in another piece. For example, a failure of the catalytic converter or O2 sensor. Service Director Dan Burns says “Sometimes we find one or the other is the issue. From there, maybe the o2 sensor fails because the catalyst that’s in the catalytic converter is failing, so as that breaks down it goes through the exhaust system and is getting on the o2 sensor – in that sense, the o2 sensor can be a canary in the coal mine”
5. Looking for a more DIY approach? You can purchase a small computer from a local auto parts store or Amazon and plug it into a port in your car.  Called an OBD-II scanner, it can read the diagnostic trouble codes stored in your car’s computer. However, know that the codes are often just the information that can then be used to do a hands-on diagnosis of the issues. 

Your Check Engine Light is an early warning system – back in the day, you used to only be able to tell that your car had an issue because it was actively breaking down. It wasn’t even that long ago that there was no standardized check engine light in vehicles the way we know it today- it wasn’t mandated and standardized in the United States until 1996. The Check Engine Light is an early warning system to alert you that some function is beginning to not operate as it is supposed to, so you can avoid a breakdown before one happens.

It’s important to always reference your owner’s manual when it comes to this light, or any other light that comes up on your dashboard.