Is It Safe to Drive with the Check Engine Light On?

The check engine light is tied into your car’s onboard diagnostics system, and it’s designed to light up (usually in yellow) whenever something goes wrong with this complex collection of components and sensors. Problems in the electronic control system are stored in a “trouble code” to identify the source of the issue. An electronic scan tool or diagnostic computer is used to indicate the problem, which is then mechanically addressed by a certified technician.

5 Reasons the Check Engine Light is On:

The check engine light could illuminate for a number of reasons, the 5 most common being your:

1. Oxygen sensor needs replacing. This sensor tracks the amount of unburned oxygen in your car’s fuel system. Without fixing, a faulty sensor leads to bad fuel economy and potential spark plug and catalytic converter damage.

2. Broken, missing, or loose gas cap. The gas cap seals the fuel system, and if it’s not there or damaged, you may lose fuel through evaporation and take extra trips to the gas station.

3. The catalytic converter is failing. The catalytic converter transforms carbon monoxide into carbon dioxide. If broken, your car will have poor engine performance and fuel efficiency and won’t pass an emissions test.

4. Mass airflow (MAF) sensor needs replacing. To determine how much fuel is needed to economically run the engine, the mass airflow sensor tracks the amount of air entering the engine. A bad airflow sensor leads to bad fuel efficiency and engine performance and could damage the spark plugs, catalytic converter, and oxygen sensor.

5. Spark plugs or wires need replacing. The spark plugs and spark wires work together to ignite the air-fuel mixture in the combustion chamber and transfer the spark from the ignition coils to the plugs. Bad spark components also lead to poor engine and fuel performance, as well as damaged ignition coils, oxygen sensors, and could clog a catalytic converter.

Determine if it's Safe to Drive in 3 Steps:

Whether or not it’s safe to drive with the check engine light on depends on vehicle performance with the light on and the root cause of its illumination. Regardless, you should always have your car inspected as soon as possible after the light turns on. If the check engine light comes on while driving, follow these 3 steps to ensure it’s safe to continue driving or if you need to stop immediately:

1. Determine if the problem requires immediate attention. In addition to the check engine light, your dashboard may also indicate low oil pressure or overheating issues. Pull over and shut off the engine as soon as you can if these lights also illuminate. Some cars may have a red check engine light to alert you to stop right away, while a yellow light stands for investigation.

2. Reduce speed and load, if possible. If vehicle performance problems accompany the check engine light, lower your speed and take it easy on the engine. Avoid speed surges erratic shifting. If you’re towing a trailer or carrying heavy equipment, try to unload as soon as you can to prevent potentially pricey repairs.

3. Check your gas cap. Especially if the light comes on shortly after refueling, pull over and check that your gas cap is tightly in place. This often solves the issue, though it may take several restarts of the engine to reset the light. The light comes on because it detects a leak in the evaporative emissions system, although many newer car models include a gas-cap specific indicator light.

Is it Safe to Drive with the Check Engine Light On?

If the check engine light comes on while you’re driving, it can be unnerving. Don’t panic, though. Take a moment to see if the car is driving any differently than normal. Is it bucking? Surging? Are there any unusual sounds? If nothing seems out of the ordinary, you can continue driving the car. It could be anything from a faulty oxygen sensor to a bad MAF sensor. It could also mean your catalytic converter has given up the ghost.

The check engine light means there’s a problem somewhere in your emissions system. Regardless, you’re safe to drive for now as long as the car isn’t performing strangely. Just have the check engine light checked and the problem repaired. Not repairing the problem can lead to more serious, and expensive, damage down the road.


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Chevrolet Cobalt - Check Engine Light is on - Kissimmee, Florida
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BMW Z4 - Check Engine Light is on - Orlando, Florida
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29 years of experience
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Marco
29 years of experience
Dodge Sprinter 2500 - Check Engine Light is on - Redlands, California
Marco was on time, friendly and very knowledgeable of what was going on with my van, I’m very happy with the service I received today, will definitely be working with your mechanic.com again.
Kia Soul - Check Engine Light is on - Riverside, California
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Chrysler PT Cruiser - Check Engine Light is on - Norcross, Georgia
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JOHNNY
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Toyota Camry - Check Engine Light is on - Carmichael, California
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