A Check Engine Light (CEL) is concerning enough itself, but things get more alarming when it starts flashing.
Get answers to these questions and learn more about the Check Engine Light flashing.
This Article Contains:
- What Does a Flashing Check Engine Light Mean?
- What Should You Do if Your Check Engine Light Flashes?
- 6 Common Reasons Behind a Flashing Check Engine Light
- What Are the Key Symptoms Accompanying a Flashing Check Engine Light?
- 4 FAQs about a Flashing Check Engine Light
Let’s get going!
What Does a Flashing Check Engine Light Mean?
A flashing Check Engine Light indicates serious trouble with your car and demands immediate attention. The most common reason behind the Check Engine Light flashing is an engine misfire.
The warning appears as an engine outline that blinks once every second. Some cars may use a steady red Check Engine Light instead of a flashing amber-colored symbol to signal a severe problem.
What should be your next step if you encounter a flashing CEL on your car?
What Should You Do if the Check Engine Light Flashes?
Driving while this warning light blinks can damage the catalytic converter due to overheating from engine misfires. An overheated catalytic converter is also a potential fire hazard.
Additionally, engine misfires cause power loss while driving and can put you in a dangerous situation on the road. If you have a misfire due to mechanical reasons rather than fuel delivery or ignition issues (e.g., worn piston rings, timing belt issues, etc.), you might be looking at high engine repair costs to fix the damage.
Now, let’s get to the causes that trigger this flashing light.
6 Common Reasons Behind a Flashing Check Engine Light
Multiple factors can cause an engine misfire, which triggers a blinking light on the dashboard – fuel delivery issues, a bad engine sensor, to name a few. We’ll touch on them here.
1. Faulty Spark Plug
Bad spark plugs usually cause an engine misfire and, thus, a flashing engine light. A malfunctioning spark plug won’t provide the required high-voltage spark for igniting the air-fuel mixture in an engine’s cylinder, causing a misfire.
2. Bad Ignition Coil
An ignition coil transforms low battery voltage into a high-voltage spike for the spark plug to function. The coil may be placed directly on top of each spark plug in the case of a modern vehicle’s engine or connected using spark plug wires in a distributor-type ignition system.
3. Defective Fuel Injector
A bad fuel injector won’t provide enough fuel to the cylinder for combustion, leading to a lean condition and a misfire.
4. Engine Sensor Problems
The mass airflow sensor measures the air entering the engine. If this engine sensor is faulty, it can mess up the air-fuel ratio, resulting in a misfire.
5. Faulty Oxygen Sensor
The oxygen sensors in your car’s exhaust system help the ECM adjust the air-fuel ratio and keep a check on the efficiency of the catalytic converter. An engine misfire can occur due to an incorrect air-fuel ratio reading from an oxygen sensor.
6. Vacuum Leak
A damaged vacuum hose or intake manifold gasket allows unmetered air to enter the engine. This leads to a vacuum leak, resulting in an engine misfire and a flashing CEL.
Next, we’ll cover the noticeable symptoms you may experience along with a flashing engine light.
What Are the Key Symptoms Accompanying a Flashing Check Engine Light?
Here are the common signs that your engine is misfiring and causing the Check Engine Light to flash:
- Car shaking: If a cylinder misfires, it’ll cause the crankshaft to slow down suddenly because of a loss of turning effort, resulting in a shaking car. You may also experience rough idling.
- Loss of power: A misfire always means incomplete or no combustion of fuel in a specific cylinder — reducing power output from the misfiring cylinder and, eventually, engine performance. You may experience it in the form of slow acceleration.
- Abnormal sounds: If you hear an unusual popping, sputtering, or backfiring sound from your car, it could be due to the unburned fuel igniting in the exhaust system after a misfire.
- Poor fuel economy: Inefficient combustion because of an engine misfire leads to unburned fuel in the exhaust gas, resulting in poor fuel economy.
- Failed emissions test: Engine misfires increase the hydrocarbon content in the exhaust gas due to incomplete combustion and can lead to a failed emissions test.
Have more questions about the Check Engine Light flashing on your dashboard?
Let’s address them.
4 FAQs about a Flashing Check Engine Light
Here are answers to some common questions about this flashing light.
1. How Is a Steady Check Engine Light Different from a Flashing One?
A steady or solid Check Engine light generally means something is off with your vehicle’s engine or emissions control system (catalytic converter, O2 sensor, etc.), or you have a loose gas cap. It doesn’t always indicate a severe problem, unlike its flashing counterpart.
You can still drive your car with a solid Check Engine Light. However, you should reach out to an auto repair professional promptly to avoid serious issues later.
2. What Are the Common Flashing Check Engine Light Codes?
The following Diagnostic Trouble Codes (DTCs) can be present along with the Check Engine Light flashing on the dashboard:
- P0300: Random or multiple cylinder misfire detected
- P0301: Cylinder 1 misfire detected
- P0302: Cylinder 2 misfire detected
- P0316: Engine misfire detected on startup (First 1000 revolutions)
3. Does Every Misfire Result in a Flashing Check Engine Light?
No, only “Type A” misfires result in a flashing Check Engine Light. They are identified by calculating the percentage of misfires during a 200-revolution interval of the crankshaft. Type A misfires can damage the catalytic converter.
Type B misfires are detected by considering a 1000-revolution interval and don’t pose a direct threat to the catalytic converter. They can, however, raise the emission levels to 1.5 times higher than the Federal Test Procedure (FTP) standards and are indicated by a steady Check Engine Light.
4. Why Is the Check Engine Light Flashing after Changing the Spark Plugs?
The blinking check engine warning light may come on after replacing a faulty spark plug on your car because of:
- An incorrect spark plug gap
- A spark plug wire without a proper connection to the plug or ignition coil
- A loose coil connector in a distributor-less ignition system
- A plug isn’t tight enough
- A damaged ignition coil
A flashing Check Engine Light is mostly caused by engine misfiring and demands immediate attention. Ignoring the blinking Check Engine Light can damage the catalytic converter – an expensive exhaust system component, or lead to baffling engine repair bills. If there’s a Check Engine Light flashing on your dashboard, contact an auto repair shop promptly and get your car towed to it.
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