5 Reasons Your Check Engine Light May Be On (& What To Do)

September 25, 2019 · 7 min read

Updated February 18, 2026

Executive Summary

Your vehicle’s OBD-II system triggers the check engine light, and it doesn’t automatically mean a major repair -it signals that something in the engine or emissions system needs attention.
Common causes include a faulty mass airflow (MAF) sensor, a bad oxygen (O2) sensor, worn spark plugs, a failing catalytic converter, or even a loose gas cap; some simple, others more serious.
Symptoms like rough idling, reduced fuel economy, poor acceleration, strange exhaust smells, or trouble starting can help narrow down the issue.
Ignoring the check engine light can lead to larger, more expensive repairs over time and may impact performance, emissions, and overall vehicle lifespan.

If you’ve ever seen the little check engine light appear on your dashboard, you’re definitely not alone. It’s one of the most common things drivers see, and it can cause a lot of confusion. Here’s the good news: it doesn’t automatically mean a huge repair bill is necessary! Sometimes it is super simple, but there may be the occasional larger issue. Either way, it’s important to know the common reasons behind the light appearing that can save you time, stress, and money.At Toyota of Clermont’s service center, we see this light all the time. Today, we’re Making It Simple® and explaining what might be causing the check engine light to turn on and what to do to make the best decision for your vehicle and budget!

What The Check Engine Light Means

The check engine light is part of your car’s On-Board Diagnostics (OBD-II) system, which is basically how your vehicle tells you something is operating within its normal parameters. This can cover any issue from emissions to engine performance to a loose gas cap. Just keep in mind the light itself doesn’t exactly tell you what’s wrong, but instead something triggered the vehicle’s internal system to flag a concern. That’s where knowing the common causes comes in handy, so let’s get into the top five reasons!

A Check Engine Light Indicates: You Need A New Mass Airflow (MAF) Sensor

The mass airflow sensor helps your vehicle determine how much air is coming into the engine so it can balance fuel and air for optimal combustion. If the sensor notices something wrong (such as it's dirty, failing, or damaged), then it can end up throwing your engine’s balance. Symptoms besides the check engine light coming on may include:

Trouble with acceleration
Hesitation during normal driving
Reduced fuel economy

The sensor can get dirty over time, which then sends inaccurate readings to your engine’s system. In some cases, cleaning the sensor will solve the issue, but often a new MAF sensor is needed for long-term performance. Lucky for you, our technicians at Toyota of Clermont can run a sensor test and let you know if cleaning or replacing it is the best option. Toyota service center

A Check Engine Light Indicates: Your Catalytic Converter Has Gone Bad

Your Toyota’s catalytic converter is a key emissions component in your exhaust system. It converts harmful gases into less harmful ones before they exit the tailpipe. If it fails, your vehicle may still run, but it won’t run efficiently. You might notice other issues such as:

Reduced fuel economy
Higher exhaust heat
Trouble passing emissions tests
Strange smells (sometimes like rotten eggs)

A failing catalytic converter is one of the more serious reasons your check engine light may come on. Since it’s so closely tied to emissions and overall engine efficiency, you’ll need to address this problem sooner rather than later to prevent it from escalating into something worse. At the Toyota of Clermont Service Center, we can verify if your catalytic converter is the culprit for your check engine light popping on, as well as help you understand your options and what replacement may involve.

A Check Engine Light Indicates: Your Spark Plugs Need Replacing

Spark plugs are important for your engine to start and run smoothly. They’re responsible for igniting the fuel-air mixture inside the engine combustion chamber. When they wear out, it can negatively impact everything from starting your car to maintaining speed on the road. Signs your spark plugs might be the cause behind your check engine light include:

A rough idle state
Trouble starting your car
Reduced fuel efficiency
Stalling or misfires

Worn spark plugs also put extra stress on other components in your car, such as the catalytic converter and oxygen sensors. What may start as a spark plug problem may snowball into something much larger, so getting your regular car maintenance helps keep your engine performing well (and your check engine light off). Engine maintenance for Toyotas

A Check Engine Light Indicates: You Have A Bad Oxygen (O2) Sensor

Your oxygen sensor (also known as the O2 sensor) plays a crucial role in monitoring the amount of unburned oxygen in your car’s exhaust. This data helps your vehicle determine if it’s running a rich or lean fuel mixture! When the oxygen sensor fails, the engine’s computer can't make accurate adjustments and will turn on the check engine light as a heads-up. You may also notice indicators such as:

Inefficient engine performance
Poor fuel mileage
Increased emissions

The O2 sensor directly impacts your car’s burn efficiency and emissions control, so catching the issue before it grows worse is important. If you think there’s an issue with this sensor, bring your Toyota in for our technicians to check it out to help you avoid higher fuel costs and protect other components from damage.

A Check Engine Light Indicates: Your Gas Cap Isn’t Tightened All The Way

Believe it or not, this is often the simplest and most common cause of the check engine light turning on. Your gas cap helps to maintain the pressure inside your fuel tank and prevents fuel vapors from escaping into the air. If it’s loose or not sealed properly, your vehicle’s emissions system can interpret it as a leak and illuminate the check engine light.This is the easiest indicator to fix. Just safely pull over, turn your car off, then check your gas cap to see if it's tightened (make sure to hear it click at least a couple times). Usually, the light will turn off once you start driving again.

What If You Ignore Your Check Engine Light?

You might be tempted to ignore your check engine light if your car seems to be running fine, but modern vehicles are incredibly connected. One small problem left unchecked can lead to bigger, more costly issues over time. Even more importantly, ignoring warning lights can put extra stress on your engine and reduce the lifespan of key components in your Toyota. It can also lead to issues that affect performance and safety, which can be a greater risk. Car engine issues

Visit our Service Center With Any Issue Today!

Now you know what to do the next time your check engine light turns on, so no need to panic! If you need a technician to check out your engine, Toyota of Clermont is here to help. Schedule an appointment at our Service Center to get your car checked out by giving us a call at 352-404-7001 or booking online. Or, come visit us in person at 16851 State Road 50.

Common FAQs for Check Engine Lights

What is a catalytic converter?

A catalytic converter is a crucial part of your car’s exhaust system that takes the toxic gases and pollutants from the engine’s exhaust and turns them into less harmful emissions through a chemical (redox) reaction. It helps reduce the amount of dangerous pollution released into the air and is required on gasoline-powered vehicles by law in many places.

Why won’t my car start?

Your car might not start for several reasons: the battery is dead and can’t power anything, the starter is broken so it can’t turn the engine over, the fuel filter is clogged and preventing gasoline from reaching the engine, the alternator isn’t charging the battery, or the spark plugs are worn out and can’t ignite the fuel.

What are spark plugs?

A spark plug is a small part that fits into your engine’s cylinder and creates a tiny electrical spark to ignite the air-and-fuel mixture so the engine can start and run. Without that spark to start combustion, your car wouldn’t be able to begin moving.

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Feb 04, 2026 in Toyota Service

What To Do if Your Hybrid Car Battery Dies: The Ultimate Guide

Hybrid vehicles are known to be reliable, fuel-efficient, and offer a long-term battery life. However, when a hybrid car battery problem does happen, Toyota of Clermont is here to help. We know it can feel overwhelming while having two different battery types. There’s a standard 12-volt battery and a high-voltage hybrid (traction) battery. Also, most vehicles that don’t start are caused by the 12-volt battery and not the hybrid battery itself. However, if the hybrid battery is failing, the situation is much more complex, and you’ll need to stop by Toyota of Clermont. We’re “Making it Simple®” by going over the signs to watch for and the next steps to take if this happens to you. The 411 on a Hybrid Car Battery The Clermont Toyota hybrid car battery (also called the traction battery) is the high-voltage battery pack that powers the electric motor and works with the gas engine. This battery is designed to last for many years and tons of miles under normal driving conditions. However, when the battery fails, the symptoms are different from those of a dead 12-volt battery. Signs Your Hybrid Car Battery is Failing If you notice your Clermont Toyota hybrid car battery failing, then the following signs might tell you if it’s that or the 12-volt battery. Let’s get into it! Dashboard Warning Messages If you see an alert that says “Check Hybrid System,” “Hybrid System Malfunction,” or other warnings, then this is a huge sign. In addition, these warnings can indicate that the vehicle’s control systems have detected an issue with the battery pack or other components. Engine Running Constantly Additionally, the gasoline engine runs almost all of the time, even at low speeds or when idling. Also, the Clermont Toyota fuel economy drops off when the electric motor isn’t assisting this as it once did. Will Not Go Into “Ready” Mode Plus, if the Clermont Toyota vehicle powers on, but won’t enter the “Ready” mode, even if the 12-volt battery has been tested or confirmed healthy, then it might be the hybrid car battery. Also, this is a strong indicator of a high-voltage system problem. Loss of Power In addition, if you notice reduced acceleration or sluggish performance, it might be due to the hybrid car battery. Plus, another sign is if the vehicle isn’t able to drive on electric power at all. What to Do if Your Hybrid Car Battery is Failing Here are some steps to take if you notice your Clermont Toyota hybrid car battery is failing! Do Not Attempt DIY Auto Repairs Hybrid batteries operate at a very high voltage, which can be dangerous without taking proper precautions. First, be sure never to remove battery covers or panels. Also, don’t touch or disconnect orange-colored cables (including high voltage components). Lastly, don’t attempt to fix this yourself at home. High-voltage systems should only be handled by places like Toyota of Clermont to ensure that safety is the top priority. Have a Toyota of Clermont Check it Out Next, ensure that there’s a proper hybrid car battery inspection. If something breaks down, it’s important to have the vehicle towed or carefully driven to a dealership. The auto service technicians will scan the vehicle’s control modules, retrieve the diagnostic trouble codes, test the health, and check other related systems like cooling fans and wiring. Having this done will ensure you’re not replacing the hybrid car battery when the problem could be something much less costly. Ask About Battery Repair or Replacement Options Also, be sure to ask about battery repair or replacement options when you bring your vehicle to our dealership. Here are some things to check out! New OEM Hybrid Battery Purchasing a new OEM hybrid battery is the best option. Also, this means it’s backed by manufacturer support and warranty, and it’s the most expensive choice upfront. Remanufactured or Reconditioned Battery In addition, the hybrid car battery is significantly more affordable than a brand-new one. Also, individual battery modules can be replaced or balanced. Lastly, quality and longevity depend on the rebuilder. Used Battery from a Salvage Vehicle In addition, this option provides the lowest cost upfront. However, the lifespan is uncertain and depends on the age, mileage, and storage conditions. Lastly, this is best suited as a short-term solution, so keep that in mind for your budget. Check the Warranty You should always check the warranty for your hybrid car battery before stopping by our dealership. However, we can help you, too! Most hybrids come with extended warranties that often last 8-10 years. Tips for Long-Term Battery Care Additionally, we have some great tips for you for long-term battery care! Check them out! Drive regularly. Long periods of not driving can stress out the battery. Also, avoid extreme heat when possible. Try to park in a shaded area and avoid direct sunlight. Lastly, keep battery cooling vents clear (often near the rear seats ro cargo area). Stop by Toyota of Clermont! Need to check out a hybrid car battery? Stop by Toyota of Clermont at 16851 State Road 50, just west of the Florida Turnpike. We’ll get you into the vehicle of your dreams!

Jan 15, 2026 in Toyota Service

How to Choose an Auto Mechanic Near Me

If you’re searching for an “ auto mechanic near me,” look no further than Toyota of Clermont! We know finding a reliable auto mechanic near you takes a lot of time and effort, but we’re “Making it Simple®” to do just that. Some key factors to consider are solid credentials, positive reviews, clear communication, and fair, transparent pricing. Taking a little extra time to vet a mechanic will save you time in the long run in case an emergency happens. Let’s dig into more things you should look for! Begin with Recommendations First, you should always begin with recommendations. If you have a friend or co-worker who has had positive results with a mechanic, then you should try that person, too! At Toyota of Clermont, we offer the best equipment and have genuine Toyota parts for your vehicle. Also, you should ask who they use, what work was done, and whether the shop guaranteed the repairs and offered a warranty. When searching for an “auto mechanic near me,” you should search for these shops online and see what you can find about them. In addition, between word-of-mouth and consistency, you’ll find the best shop. Although Toyota of Clermont should really be at the top of your list! Check the Credentials and Certifications of an Auto Mechanic Near Me Secondly, you should check the credentials and certifications when searching for an “auto mechanic near me.” At Toyota of Clermont, we’ll give you peace of mind that your vehicle will be in good hands. Be sure to check for technicians who are certified, which means that they’ve passed tests and stay certified so that they’re up to date with the latest auto repairs. Plus, Toyota Certified Technicians have completed a full series of exams in areas like brakes, engines, and electrical systems, a strong indicator of deep expertise. In addition, if you drive a specific brand, check if the auto shop has manufacturer-specific training or certifications. Additionally, some Clermont Toyota auto shops offer programs like AAA Approved Auto Repair that require technician training and customer satisfaction. Check Reviews with an Auto Mechanic Near Me Next, you should check the reviews when you’re looking for an auto mechanic for your Clermont Toyota vehicle. When looking for an “auto mechanic near me," online reviews are king. You should check for sources like Yelp, RepairPal, or similar platforms. Also, pay attention to similar things that happen, as this could be a positive or negative trend happening at this body shop. However, at Toyota of Clermont, you’ll always be in great hands! In addition, don’t let one bad review scare you. Look at how the shop responds to a customer who had a bad auto service or auto repair. Stop by the Body Shop Before You Commit The next step you should take is to stop by the body shop for a small auto service like an oil change or a tire rotation. While you’re there, take a look at the store and see if it looks organized, the equipment seems modern, and vehicles are handled with care. Also, talk with the service advisor and ask simple questions about car maintenance. Toyota of Clermont will always provide you with a comprehensive list of things to keep an eye on with your vehicle. Be Sure to Ask the Proper Questions Also, when searching for an “auto mechanic near me,” be sure to ask the right questions. When you’re evaluating whether or not to select a mechanic. Here are some questions you should ask: Are your technicians ASE certified, and is anyone an ASE Master Technician? What kind of warranty do you offer on parts and labor? Do you provide written estimates and get approval before doing additional work? If you’re at a quality shop, they’ll typically offer a 12‑month/12,000‑mile warranty on repairs and are very clear about what it covers. Additionally, they document estimates, explain line items, and never proceed with extra work unless you approve of it. Evaluate Communication Through Both Parties Also, when you’re searching for an “auto mechanic near me,” check if the person communicates clearly. If you’re in the hands of a reliable mechanic, they’ll communicate clearly about what’s wrong, what needs to be done, and how long this auto repair will take. In addition, you should receive updates throughout the process, if this costs more than quoted, and answer any questions you have. Be sure to check for shops that are upfront about everything wrong with your vehicle. Also, check that you understand the diagnostic process and the labor rates rather than giving a ballpark number. Lastly, it’s super important to have transparent pricing, written invoices, and to walk you through everything. Don’t Let the Price Bog You Down Don’t let the price bog you down when it comes to this. Convenience is important. However, don’t sacrifice quality for convenience. Plus, don’t pick someone because they offer the lowest price, because they might offer parts that aren’t genuine and don’t have a warranty. Build a Relationship with an Auto Mechanic Near Me When searching for an “auto mechanic near me,” it’s important to build a relationship before your vehicle breaks down. By using this shop for routine car maintenance, you’ll build a long-lasting relationship based on trust. As the trust grows, you’ll continue to visit them for bigger auto repairs, too! Visit Toyota of Clermont Today! If you’re searching for an “auto mechanic near me,” be sure to visit Toyota of Clermont! We’re located at 16851 State Road 50, just west of the Florida Turnpike. We’re here to get your vehicle back on the road, whether it’s a Toyota or another make!

Sep 28, 2023 in Toyota Service

Choose the Best Toyota Tundra Lift Kit By Clermont Toyota Experts

The Toyota Tundra is the largest truck on the American lineup, with the Toyota Tacoma as the second. You can even make it larger by adding modifications like a Toyota Tundra Lift Kit right here at Toyota of Clermont. However, before you go making these changes, there are a few things we need to catch you up on, for you to get the best lift kit possible for your truck. What Are Lift Kits? A lift kit allows you to increase the ground clearance between your Tundra and the pavement. There are three main different types of lift kits: Leveling kit, suspension lift, and body lift. The purpose of a lift kit for your Clermont Toyota can vary from car owner to car owner, however, we’ll get into how you can choose which lift kit is right for you. Leveling kit Your Clermont Toyota Tundra’s front section is lower than the rear section, known as “rake”, and is designed to cause less wear on your suspension with added weight in your truck bed. If you are looking to add slightly larger tires or rarely haul heavy, a leveling kit is the right pick for your Toyota Tundra lift. Suspension lift Get a suspension lift kit for your Toyota Tundra if you’re looking to elevate your road visibility, get bigger tires, or upgrade your off-roading performance. Why? Well, a suspension lift works by raising your overall height of the Tundra, increasing your ground clearance for better performance on the rocky pavements. These tend to be a little bit more expensive than leveling kits or a body lift, however, they’re worth it if you are looking for an elevated off-roading experience in your new 2024 Toyota Tundra. Body lift These lift kits increase the distance between the body and the frame of the vehicle to allow you to get bigger tires for your Clermont Toyota Tundra. It doesn’t modify your truck’s performance, it’s mostly just to look cool and drive higher. Where can you buy a Toyota Tundra lift kit? The good news is that Toyota saves out with their special lift kit for the Toyota Tundra and you can get it at our dealership, Toyota of Clermont. If you are looking for a Toyota-vetted lift kit, Toyota blew it out of the park with this one. Let’s check out some of the advantages of the Toyota-supplied lift kit versus aftermarket options. The lift kit works and has been tested with the Toyota Safety Sense System to ensure that forward-collision warnings and adaptive cruise control work with the modifications. This package adds 2.6 inches of ride height for better approach and departure angles Adds new shocks, taller front coil springs, forged upper control arms from Roush Performance, front extended driveshafts, rear spring spacers, front stabilizer links, new lower knuckles, bump stops, and outer tie rods. Find a lifted Toyota Tundra for sale at our dealership in Clermont, FL. Looking for a Toyota Tundra lift kit? Visit Toyota of Clermont Our expert techs are here to help you modify your Clermont Toyota Tundra lift kit as easily as possible. Come visit our experts at Toyota of Clermont to get your vehicle ready to handle whatever the off-beaten paths throw at you. Call us at (352) 404 – 7000 to get things set up!