Is It Safe to Drive Your Vehicle with a Check Engine Light On?

By Lori Straus

Whenever the check engine light has come on in our family vehicle, I’ve certainly panicked. If something’s wrong with the engine, that’s bad! Will the car explode? Likely not. In this blog post, I’ll explain a few checks that can help you decide if it’s still safe to drive your vehicle with the check engine light on.

OBD-II Diagnostic Tools

Every vehicle manufactured since 1996 has an OBD-II port, sometimes written as OBD-II. OBD stands for “onboard diagnostic,” and the “2” signifies second generation. This is a standardized feature in all vehicles and connects to your vehicle’s black box. So, when your check engine light comes on and you take your vehicle to your mechanic, your mechanic will connect his OBD-II diagnostic tool to the port to understand why the check engine light has come on.

You can buy your own diagnostic tool and use it to tell your mechanic over the phone what may be causing the problem. Your mechanic can then help you decide when to bring the vehicle in. Without the tool, though, you can still get an indication of how important that light is.

If you buy an OBD-II diagnostic tool, do your research. They range in price from $30 to over $300.

Check Engine Light Is Off

A darkened check engine light doesn’t guarantee that your engine isn’t having any problems. But rather, your check engine light off means that if your engine is having problems, the computer is managing them just fine and has determined there’s no need to notify you.

Check Engine Light on But Solid

Close-up of lamps on the instrument panel are on.

This is a grey zone and where an OBD-II diagnostic tool comes in handy. When your check engine light is on but solid, it can mean any number of things. For example, your gas cap might be loose. That’s obviously a quick fix: pull over to the side of the road and tighten the cap. If your engine light came on right after you filled up, this is the likely cause.

However, because the check engine light can indicate a malfunction in, not only the engine but also in the exhaust and fuel systems,  you will still need to take it to your mechanic soon. Call them as soon as possible. (That doesn’t mean a week later.) If you have a reliable OBD-II diagnostic tool, plug it into your OBD-II port (likely under your steering wheel, but check your owner’s manual) and see what it says. At the very least, you have the information you can give your mechanic when you call to make an appointment.

Check Engine Light on and Flashing

A flashing check engine light is more severe than a solid light. If your check engine light is flashing, pull over and do a quick self-check of your vehicle:

  • Do any of the other indicators on your dashboard point to a potential problem, for example, an overheated engine or coolant?
  • Do you see any fluid leaking underneath your vehicle?
  • Is there any smoke?

If the answer to any of these questions is yes, do not start your engine. Instead, have it towed to your mechanic. Although we’re used to playing “the gas game” to see how long we can drive on fumes, you don’t want to take the same risk with the engine light.

If you have an OBD-II diagnostic tool, gather the information it gives you and call your mechanic immediately.

Take the Engine Light Seriously, but Don’t Panic

The difference between the solid light and the flashing light is the severity of the problem, which translates into how soon you must get your vehicle to a shop. But you do have a problem. If the light is solid, check your gas cap. If it’s on tight, you’re likely fine to drive to your destination and then call your mechanic. But if the engine light is flashing, pull over as soon as it’s safe and call. You don’t want to chance a major engine event while you’re on the highway.