When your car’s check engine light comes on it can be a nerve-wracking experience. For the average driver, the uncertainty and trepidation that a check engine light creates can feel like getting a bad medical diagnosis that doesn’t actually tell you what’s wrong or how to fix it. Instead of worrying, consider taking the following steps to discover if you’re dealing with a larger repair or something as small as a loose gas cap. 

Look for Problems That Require Immediate Attention

If your check engine light comes on, there are several things that you can do right away to see if something is wrong. Investigating these can either provide you with a quick fix, help you rapidly identify a bigger problem, or, at the least, allow you to instantly eliminate some of the possible issues. Problems that require attention as soon as the check engine light comes on include:

• A missing cap in your engine: If liquid is exposed, it may trigger your check engine light.
• An unplugged or loose wire: A wire can loosen on its own or be destroyed by an outside force, such as a mouse or squirrel, which can quickly set off a check engine light as well.
• Low oil pressure: If your car is low on oil, it can cause your check engine light to go off. This is often shown in its own glowing light along with the check engine light on the dashboard.
• Overheating: If your car’s engine temperature is heating up, it can once again trigger the check engine light. If you see the temperature gauge rising, stop as soon as possible.

Some of these issues are easy DIY repairs, such as adding more oil or replacing a cap. However, if your car is overheating or an internal wire has been chewed by a mouse, it may require a trip to the mechanic. 

Some models will have a yellow version of the light to indicate that you should check for a problem and a red one if the system believes you should stop immediately. If you aren’t certain that this is the case, though, you should always pull over as soon as possible no matter what specific color indicator you’re seeing.

Regardless of the scope of the repair itself, if your check engine light comes on when your car breaks down, it’s important that you assess the situation carefully, avoid doing on-the-spot repairs, and generally stay safe until you get your car towed to a shop where it can be properly diagnosed.

Make Sure Your Gas Cap Is Tight

One of the most common culprits that can trigger the check engine light is the easiest to repair. If you put your gas cap on incorrectly, loosely, or in a way that doesn’t create a proper seal, it can quickly cause that dreaded check engine light to turn on. Often all that is required is to check the cap and fix it if it’s not on correctly.

If this is the case, it’s important to realize that the light may not turn off for several trips after you fix the cap. You can risk driving during this time in order to see if the light turns off. However, it’s generally advisable for you or a mechanic to perform a diagnostic test first (more on diagnostics further down). This allows you to confirm that, by making these extra trips, you aren’t exacerbating a separate issue that triggered the light in the first place.

Reduce Your Load Size

Both your speed and excessive weight can put extra pressure on your vehicle’s engine. For instance, if you drive fast on highways regularly or you have a hitch on a smaller vehicle, you may be overtaxing the capabilities of your engine. This can lead to a loss of power, which may trigger your check engine light.

If this is the case, you may be able to address the issue by simply reducing the demands you’re putting on your vehicle. Remove the size of the loads that you’re pulling, at least for a while, and don’t drive as quickly to see if it causes the check engine light to turn off. 

Once again, even if you suspect load size or speed to be the case, it’s still recommended that you conduct a diagnostic check. Make sure that there isn’t something else going on and check to see if you already caused any damage that could get worse.

Perform a Diagnostics Test

The number one thing that you should do when the check engine light comes on is to perform a diagnostic test.

The check engine light is an outward-facing part of your vehicle’s onboard diagnostic system. In other words, it’s a part of an internal computer system that oversees your vehicle and watches out for any number of problems. To understand the sheer size of potential issues that could arise, consider the fact that Innova’s diagnostic database and apps are designed to diagnose over 3 million possible automotive issues.

Depending on your comfort and level of knowledge, either you or a professional can use an OBD1 or OBD2 diagnostic tool to discover what particular issue triggered the check engine light in your system.

Click here if you're looking for OBD2 scan tool recommendations by Innova in 2024.

Avoid Emissions Testing

Finally, make sure to avoid emissions testing until you’ve fully resolved your check engine light concerns. Emissions testing is a requirement in many states to ensure that your vehicle isn’t producing too many emissions.In some states, a check

engine light will be a serious concern that could cause you to fail your test. In other states, the mere fact that the light is on is an automatic fail. This is true even if the light was only triggered by a loose gas cap or wire. 

Once you’ve resolved the issue, you may need to drive for a while before you can pass your emissions test. Typically it’s suggested that you drive between 50 and 100 miles before taking the test in order to ensure that the system resets.

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