Few things can ruin a day faster than an unexpected car crisis.
You’re driving to work, on your way to dinner with friends or taking the kids to soccer practice when something on your dashboard catches your eye: a warning light. It might appear as a glowing orange engine symbol, or as bold, intimidating type: CHECK ENGINE. It is one of the most dreadful sights an unsuspecting driver can experience. Your heart sinks while unimaginable possibilities rush through your mind: What does this mean? Do I need a new engine? How much would that cost? Maybe it’s time for a new car? Why me?
Relax and take a deep breath. When this particular warning light appears, don’t panic. And no, don’t start shopping for a new car just yet.
What is a Check Engine Light?
A check engine light is a warning light on the dashboard of a vehicle that indicates a problem with the engine or emissions system. It is also known as a malfunction indicator lamp (MIL) or service engine soon (SES) light. When the check engine light comes on, it means that the vehicle’s onboard diagnostic (OBD) system has detected an issue with the engine or emissions system that needs attention.
The check engine light can be triggered by a wide range of issues, from minor problems such as a loose gas cap to more serious issues such as a faulty oxygen sensor or catalytic converter. In some cases, the check engine light may come on even if the vehicle is still drivable, but it’s important to address the issue as soon as possible to prevent further damage or emissions issues.
What Does a Check Engine Light Mean?
Let’s walk through what the CHECK ENGINE light means and what you need to do about it.
While yes, the CHECK ENGINE light is an indication of an issue related to your car’s engine (apparently one of its most essential components), alerting you to the fact that something is not operating as it was designed to, it is often not as bad as that ominous warning might indicate.
The CHECK ENGINE Light is a component of the car’s On-Board Diagnostic (OBD) system, which is part of the car’s brain or computer, which monitors all critical systems for proper functioning. When one of the many sensors within the system detects a fault, it records the data as a code in the computer and activates the appropriate warning device: in this case the CHECK ENGINE light on the dashboard.
And no, it does not mean that your car’s engine is going to blow up or drop onto the road, leaving you stranded. This warning is rarely the result of a mechanical problem, something breaking, but rather a heads-up regarding your car’s fuel and emission systems.
Your car’s engine takes in air and gas and ignites this pressurized mixture with a spark from your spark plugs, causing internal combustion or explosion within the engine cylinders, causing the engine to run. The constant cycling of this process is what drives the motor, and thus the car. After each small explosion, the fumes from the combustion are exited through the exhaust system. The precise control of this fuel/gas mixture and process, along with the components of the system, which include things like the mass airflow system (MAS), oxygen sensors, catalytic converter(s) and even your gas cap, can affect not only the performance of the engine, but more specifically in this case, the quality of the exhaust fumes that exit your car.
And that is what the CHECK ENGINE light is warning of—the potential for excessive emissions and harmful toxins—beyond safe levels determined by your car’s computer system (and governed by the Environmental Protection Agency), spewing out into the environment. And it’s important to note that in states or regions that require an emissions inspection, your car will most likely not pass with the CHECK ENGINE light on.
What to Do When Your CEL Is On
So, what do you do? A good rule of thumb for any “unusual” car activity or warning is to pull over to a safe location, away from traffic, turn the car off and do a quick assessment or walk around. Check for smoke, unusual smells or dripping fluids. Then, if you see nothing out of the ordinary, aside from that annoying CHECK ENGINE light, it is probably okay to continue driving, as long as the car is performing safely. Then, since as we know, most car problems don’t fix themselves, and can quickly turn into more significant and costly repairs, it is highly advisable to get the car to a qualified shop as soon as possible. Reputable service shops that perform auto engine repair and most that do exhaust and brake service have the necessary tools to read the CHECK ENGINE fault code, provide a report showing where the error occurred, diagnose the problem and provide the necessary repairs.
In Conclusion
So, even though the CHECK ENGINE light might not indicate a terminal problem, don’t ignore it, because left as is, the problem will most likely get worse. And instead of something as simple as a faulty gas cap or a worn-out oxygen sensor, your problems could quickly escalate into a much more severe and costly repair, such as replacing catalytic converters.
Frequently Asked Questions About the Check Engine Light
What does the check engine light mean?
The check engine light, also called the Malfunction Indicator Lamp (MIL), indicates that your vehicle’s onboard diagnostics (OBD-II) system has detected a fault affecting the engine, emissions system, or related components. The light does not identify the exact problem—it simply signals that one or more diagnostic trouble codes (DTCs) have been stored and the vehicle should be inspected.
Is it safe to drive with the check engine light on?
It depends on how the light is behaving.
- A steady check engine light generally indicates a non-emergency problem, and the vehicle can often be driven carefully to a repair shop if it is operating normally.
- A flashing check engine light usually indicates an active engine misfire that can quickly damage the catalytic converter. If the light is flashing, reduce speed, avoid heavy acceleration, and have the vehicle inspected immediately. Continuing to drive may result in expensive engine or emissions system damage.
What is the most common reason for a check engine light?
There is no single most common cause, but frequent reasons include:
- A loose, damaged, or missing gas cap
- A failing oxygen (O2) sensor
- A faulty mass air flow (MAF) sensor
- Engine misfires caused by worn spark plugs or ignition coils
- Evaporative emissions (EVAP) system leaks
- Catalytic converter problems
A diagnostic scan is required to determine the actual cause.
Can a loose gas cap turn on the check engine light?
Yes. A loose, damaged, or improperly installed gas cap can cause the OBD-II system to detect an evaporative emissions (EVAP) system leak, triggering the check engine light. After tightening or replacing the gas cap, the light may turn off after several normal drive cycles if no other problems are present.
Can the check engine light turn itself off?
Yes. If the condition that triggered the warning no longer exists and the vehicle completes the required self-tests successfully, the computer may turn the light off automatically after several drive cycles. However, even if the light goes out, diagnostic trouble codes may remain stored in the vehicle’s computer until they are cleared or eventually erased by the system.
Will my car pass an emissions inspection with the check engine light on?
In most states that require emissions testing, a vehicle will not pass if the check engine light is illuminated. In addition, if the vehicle’s readiness monitors have not completed after the battery has been disconnected or diagnostic codes have recently been cleared, it may also fail or be rejected until the monitors have reset.
What should I do when my check engine light comes on?
If your vehicle appears to be operating normally and the light is steady:
- Safely pull over if necessary.
- Check that the gas cap is securely tightened.
- Watch for unusual noises, smoke, fluid leaks, or overheating.
- Schedule a professional diagnostic inspection as soon as practical.
If the vehicle runs poorly, overheats, loses power significantly, or the check engine light begins flashing, stop driving as soon as it is safe and have the vehicle professionally inspected.
Can low oil cause the check engine light to come on?
Low engine oil more commonly triggers the oil pressure warning light rather than the check engine light. However, if low oil causes engine performance problems or affects systems monitored by the engine control module, it may also contribute to a check engine light. Always address a low oil pressure warning immediately, as it indicates a potentially serious condition.
How is a check engine light diagnosed?
A technician connects a professional scan tool to the vehicle’s OBD-II diagnostic port to retrieve stored diagnostic trouble codes and live data. These codes identify the system where the fault was detected but do not automatically identify the failed part. Additional testing is usually required to determine the root cause before repairs are recommended.
Can I clear the check engine light myself?
While diagnostic codes can be cleared using an OBD-II scan tool or by disconnecting the battery on some vehicles, doing so does not fix the underlying problem. If the fault still exists, the check engine light will usually return after the vehicle completes its self-diagnostic tests. Identifying and repairing the cause of the warning is the proper solution.
Does a check engine light always mean an expensive repair?
No. Some causes are relatively inexpensive, such as replacing a gas cap, spark plugs, or an oxygen sensor. Others, including catalytic converter failure, fuel system problems, or internal engine issues, can be significantly more costly. A professional diagnosis is the only reliable way to determine the severity of the problem and avoid unnecessary repairs.
Where can I get a check engine light diagnosed in Baltimore?
If your check engine light is on, the experienced technicians at Hollenshade’s Auto Repair can perform a professional diagnostic inspection, identify the cause using advanced diagnostic equipment, explain the necessary repairs, and help restore your vehicle’s performance and reliability. Prompt diagnosis can often prevent minor issues from becoming more expensive repairs.
Contact Hollenshade’s for Baltimore Auto Repair Services Today
Is your check engine light on? Bring your car in and let our experienced Baltimore mechanics take a look. For more information or to receive a free price quote, contact Hollenshade’s Auto Repair Service today!