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The check engine light is one of the most important indicators on your vehicle's dashboard.
When it starts flashing, it's a signal that something is seriously wrong with your engine.
In this article, we’ll walk through the behind a flashing check engine light and how you can fix it before things get worse.
Most Common Cause of a Flashing Check Engine Light
A flashing check engine light is a critical warning that demands immediate attention.
The most common cause behind this flashing is typically an engine misfire.
When an engine misfires, one or more of the cylinders in your engine fails to combust the air-fuel mixture properly.
The misfire happens for several reasons.
Spark plugs are responsible for igniting the air-fuel mixture inside the engine's combustion chamber, and if they become worn out or damaged, they fail to create the necessary spark.
This leads to an incomplete burn, triggering the check engine light to flash.
Another frequent cause of misfires is a faulty ignition coil.
The ignition coil amplifies the voltage needed to ignite the spark plugs.
If the coil becomes defective, the engine can’t fire correctly, and the result is another misfire that sets off the warning light.
Fuel system can also lead to engine misfires and the accompanying flashing check engine light.
For example, a clogged fuel injector might fail to deliver the correct amount of fuel to the cylinder, causing a lean or rich mixture that misfires.
The reason why the check engine light flashes in response to these problems is that misfires allow unburned fuel to enter the exhaust system, which can cause severe overheating in the catalytic converter.
If left unaddressed, this heat can cause long-term damage, potentially even leading to a fire.
The flashing light is essentially the vehicle's way of alerting the driver to stop driving and fix the issue as soon as possible to prevent further damage.
The check engine light’s connection to the car’s onboard diagnostics system (OBD-II) allows mechanics or even vehicle owners with car scanner to read the diagnostic trouble codes (DTCs) and identify the specific cause of the problem.
Whether it’s a spark plug, ignition coil, or fuel system issue, addressing the misfire promptly can prevent costly repairs and ensure your engine runs smoothly again.
Here are some additional potential reasons:
❌Oxygen Sensor Failure: A malfunctioning oxygen sensor can disrupt the air-fuel mixture, causing the engine to misfire and the check engine light to flash.
❌Vacuum Leaks: A leak in the vacuum system can lead to improper air-fuel balance, resulting in misfires.
❌Mass Airflow Sensor Issues: The mass airflow sensor helps measure the amount of air entering the engine. A faulty sensor can disrupt combustion and trigger a misfire.
❌Catalytic Converter Damage: If the catalytic converter is not functioning properly, it can cause engine issues that lead to the flashing light.
❌Timing Belt or Chain Problems: If the timing belt or chain is worn or broken, it can affect the engine's operation, causing misfires and triggering the light.
Related Reading: This Scan Tool with GM Throttle Body Relearn Capabilities
How Long Can You Drive With the Check Engine Light Flashing
If your check engine light starts flashing, the general rule is to stop driving as soon as possible.
A flashing check engine light typically indicates a serious issue, most commonly an engine misfire that could cause significant damage if ignored.
Continuing to drive with the light flashing can result in severe damage to components like the catalytic converter.
The specific amount of time you can safely drive with a flashing check engine light varies depending on the exact issue, but generally, it’s best to minimize driving.
You might be able to drive for a few miles to get to a safer location or to a mechanic, but prolonged driving is risky.
Misfires that allow unburned fuel to enter the exhaust system can cause the catalytic converter to overheat, potentially causing permanent damage.
In addition to the risk of damaging the catalytic converter, driving with a flashing check engine light could also lead to more immediate performance issues.
For example, a misfiring engine will often run rough, causing poor acceleration, loss of power, and increased fuel consumption.
The longer you drive, the worse these symptoms can become, making the vehicle unsafe to drive.
Driving with a flashing check engine light might also cause your car to go into limp mode, which limits the vehicle's performance to prevent further damage.
Limp mode reduces the amount of power the engine can produce, limiting your ability to accelerate quickly and often capping your speed to 30 or 40 mph.
What is the First Thing You Should Do
As soon as you notice the flashing light, pull over to a safe location.
If you notice other warning signs like a rough-running engine, smoke, unusual smells, or reduced power, it’s essential to avoid driving any further.
The next step is to retrieve the diagnostic trouble codes (DTCs) using an OBD2 scanner.
These codes will help pinpoint the exact issue that triggered the check engine light.
If you don’t have a scanner, many auto parts stores offer free diagnostic services, where they will scan your car for DTCs and provide you with the results.
The codes will typically indicate problems with components such as the spark plugs, ignition coils, fuel injectors, or the catalytic converter.
Once you have the codes, you can begin to diagnose the problem or take the car to a mechanic.
If the issue seems to be minor, such as a loose gas cap, you might be able to resolve the problem quickly.
A loose gas cap can cause fuel vapor leaks, which might trigger the check engine light.
Tightening the gas cap and resetting the system could solve the issue.
However, in most cases, a flashing check engine light signifies a more serious problem.
How to Get the Check Engine Light Off
Once you’ve diagnosed the problem and addressed the issue, the next step is to reset the check engine light.
The light will turn off automatically once the problem is fixed, but in some instances, you may need to reset it manually.
Here’s how you can get the check engine light off:
First, if you used an OBD-II scanner to retrieve the trouble codes, many scanners come with an option to clear the codes after repairs are completed.
Clearing the codes will turn off the check engine light, but only do this after you are sure the problem has been fully resolved.
If the issue persists, the light will likely come back on.
Another method to reset the check engine light is to disconnect the vehicle’s battery for a few minutes.
Disconnecting the battery can reset the car’s computer, which may turn off the check engine light.
However, this method can also reset other important settings, like your radio presets and time, so it should be used with caution.
In most modern vehicles, the check engine light will automatically turn off after several driving cycles if the problem has been fixed.
A driving cycle is a sequence of operations the engine goes through, such as idling, accelerating, and cruising.
If the engine completes several of these cycles without detecting the same issue, the light will reset itself.
If the light does not turn off after addressing the issue, it’s important to double-check that the problem has been fully resolved.
A persistent check engine light could indicate that the original problem wasn’t fully fixed or that there’s a new issue causing the light to remain on.
In summary, while it’s possible to manually turn off the check engine light using an OBD-II scanner ANCEL X7 or by disconnecting the battery, the most reliable way to ensure the light stays off is to fully resolve the underlying issue.
FAQs
Can a flashing check engine light fix itself?
No, a flashing check engine light typically indicates a serious issue, such as an engine misfire. This type of problem usually requires intervention and will not resolve on its own. It is best to address the underlying cause immediately to avoid further damage.
Does a flashing check engine light always mean an engine misfire?
While an engine misfire is the most common cause, a flashing check engine light can also indicate other serious engine issues, such as problems with the fuel system, ignition system, or emissions components like the catalytic converter.
Can a dirty air filter cause the check engine light to flash?
A dirty air filter typically won't cause a flashing check engine light, but it can cause a steady check engine light in some cases if it affects the air-fuel mixture in the engine. A flashing light usually points to more urgent issues like misfires or catalytic converter problems.
