McCarthy Chevrolet Overland Park

Apr 14, 2025
5 Reasons Why Your Check Engine Light is On

Of all the car dashboard symbols in all the world, why’d it have to be the mysterious “check engine” light that starts blinking, filling your soul with a sense of impending doom, right as you leave for work or that weekend food festival you’ve been excited for? Ahh!

Calm down. Breathe. Unless your vehicle won’t turn over, begins shaking violently, or catches ablaze, there’s (probably) no reason to throw up your hands in despair. To get down to the root cause, all it takes is a trip to your local service center or mechanic for a diagnostic check-up. In many cases, the fix for your check engine light troubles is fairly simple and affordable.

But that doesn’t ease your worries, does it? (Guess it doesn’t hurt to be overly educated on the matter.) Here are 5 of the most common reasons why that pesky dashboard warning light might be showing up.

1. Loose Fuel Cap

In many instances, a flashing check engine light doesn’t indicate that there’s something seriously wrong. The moment you notice the dashboard warning light illuminate, check your gas cap – it could just be loose!

If loose, broken or missing, the gas cap may force some of your vehicle’s more finely calibrated and sophisticated systems to send false warnings. Emission control sensors, for instance, will detect that there’s air in your fuel tank or fuel vapors are escaping, which would usually be caused by a fuel line leak or something even worse.

Once the cap is tightened properly, sensors should reset after driving a few miles, automatically turning the check engine light off. Of course, if that doesn’t solve your check engine light problem, make sure you visit the nearest service professional for assistance, even if you’re on a scenic road trip.

2. Bad or Stolen Catalytic Converter 

When a catalytic converter fails or goes missing, you’ll have more car problems to deal with than just a check engine light. Your vehicle will begin moving sluggishly, get really bad gas mileage, won’t accelerate well, and produce some more obvious warning signs that something’s wrong, like emitting black exhaust that smells like sulfur—and that’s not even considering the potentially dangerous amount of carbon monoxide you can inhale. 

To replace a dead catalytic converter or one that’s stolen, you’ll have to pay for it. Due to the extensive amount of labor involved to remove and install catalytic converters, the costs can sometimes be more than the car is worth. If you find yourself in this predicament, it might be best to check out some cheap used or certified pre-owned vehicles at a car lot near you

Browse our selection of used cars for sale near Kansas City.

3. Faulty Airflow Sensor

To effectively move, your vehicle needs fuel and air. Sometimes your airflow sensor will break, causing your check engine light to turn on, but that doesn’t necessarily mean you’re on your way to owning the most expensive two-ton paperweight in existence.

With a bad airflow sensor, you can still drive your car, though fuel economy and performance will certainly decrease. Luckily this isn’t the end of the world, as replacing an airflow sensor and air filter can be done quickly and easily by a trained auto technician or mechanic near you. When you schedule your next oil change, just ask for an inspection. 

4. Spark Plugs Need Replaced

Older vehicles are the most common victims of bad spark plugs (newer models use more advanced spark plugs that can last up to 100,000 miles). Unfortunately, the symptoms of dead spark plugs are similar to many other car warning signs: stalling, bad fuel efficiency, poor performance, rough idling and, of course, a check engine light. That’s why it’s important to review your car light symbol meanings and investigate further with an OBD II diagnostic tool. 

It’s fairly easy to swap out spark plugs in vehicles these days—if you know what you’re doing. But for the everyday car owner, it’s better to have an ASE-Certified auto technician or mechanic handle it. Schedule an appointment at our Overland Park service center for an inspection.

5. Bad Oxygen (O2) Sensor 

Your vehicle’s O2 sensor, or oxygen sensor, has a very particular job: to monitor how much oxygen and unburned fuel is exhausted. Like the airflow sensor, a broken oxygen sensor won’t stop you from driving your car, though it will lower your MPG and gradually do damage to your catalytic converter. And because catalytic converters are expensive, it’s best to replace any bad O2 sensor before the damage is done. 

Schedule an Inspection at McCarthy Chevrolet of Overland Park

Of course, your check engine light could mean something else is wrong, like faulty ignition coils, a bad ECM or just a cracked hose. It’s best to get a pair of experienced eyes and hands on your car to solve the mystery. 

If you need help identifying what your check engine light or any other dashboard light means, make an appointment at our auto repair shop near Kansas City. We have professional technicians available to run diagnostics and fix the problem, no matter the type of vehicle you own. Book an inspection online or contact McCarthy Chevrolet of Overland Park at (913) 649-6000 to learn about your auto service financing options.