What will cause check engine light to blink?

A blinking check engine light typically indicates a serious problem with your vehicle's engine or emissions system. This urgent warning light requires immediate attention to diagnose and address the underlying issue before further damage occurs.

Causes of a Blinking Check Engine Light

There are several potential causes that can trigger a blinking check engine light in your vehicle:

• Misfiring Engine: A misfiring engine, often caused by faulty spark plugs, ignition coils, or other ignition system components, can lead to a blinking check engine light. This condition can cause unburnt fuel to enter the exhaust system, potentially damaging the catalytic converter.


• Catalytic Converter Issues: A problem with the catalytic converter, such as a blockage or failure, can also cause the check engine light to blink. This indicates that the converter is not effectively reducing harmful emissions.


• Fuel System Problems: Issues with the fuel system, such as a faulty fuel injector or a leak in the fuel line, can trigger a blinking check engine light. These problems can lead to an improper air-fuel mixture, which can damage the engine and catalytic converter.


• Oxygen Sensor Failure: The oxygen sensors in your vehicle's exhaust system monitor the air-fuel ratio. If one of these sensors fails, it can cause the check engine light to blink, indicating a problem with the engine's combustion process.

It's important to address a blinking check engine light promptly to prevent further damage to your vehicle's engine and emissions system. Ignoring this warning sign can lead to more costly repairs down the line.

Diagnosing and Addressing a Blinking Check Engine Light

If your check engine light is blinking, the best course of action is to have your vehicle diagnosed by a qualified mechanic. They can use an OBD-II (On-Board Diagnostics) scanner to read the trouble codes stored in your vehicle's computer, which will help identify the specific problem. Once the issue is diagnosed, the mechanic can then recommend the appropriate repairs to resolve the problem and turn off the blinking check engine light.

Addressing a blinking check engine light promptly is crucial to maintaining the health and performance of your vehicle's engine and emissions system. By taking immediate action, you can avoid more serious and costly repairs in the future.

What is the most common cause of a flashing check engine light?

The most common cause of a flashing check engine light is an engine misfire, which is a problem with the ignition or fuel delivery systems. A misfire can be caused by issues like worn spark plugs, faulty ignition coils, or clogged fuel injectors. It's important to address this immediately, as it can cause expensive damage to your catalytic converter if ignored.
 
Common causes of a flashing check engine light

• Engine Misfire: This is a failure in one or more cylinders to ignite the fuel-air mixture. 
  • Ignition system problems: This includes worn or fouled spark plugs, failing ignition coils, or bad spark plug wires. 
  • Fuel system issues: This can be caused by clogged fuel injectors, a bad fuel pump, or other fuel delivery problems. 
• Catalytic converter problems: A severe misfire can damage the catalytic converter, which is an expensive part to replace. 
• Sensor malfunctions: Faulty oxygen sensors, mass air flow sensors, or crankshaft position sensors can lead to misfires by providing the wrong data to the engine's computer. 
• Vacuum leaks: Leaks in the vacuum system can disrupt the air-fuel mixture and cause misfires. 
• Other issues: A loose or damaged fuel cap can sometimes trigger the light, though it is less common for a flashing light. 

What you should do

• Pull over safely: and turn off the engine as soon as you can. 
• Avoid hard acceleration: and drive cautiously if you must move the vehicle. 
• Get the car inspected: by a qualified mechanic immediately. 
• Do not ignore the light: Driving with a flashing light can lead to more significant and costly engine damage. 

How do you fix a blinking engine light?

A flashing check engine light indicates a serious engine misfire that needs immediate attention to prevent catalytic converter damage. To fix it, first, safely pull over and reduce speed. Then, use an OBD2 scanner to get a trouble code, which will likely point to a faulty spark plug or ignition coil, and replace the faulty component(s).
 
Immediate actions to take

• Pull over safely: A flashing light means you should stop driving as soon as it is safe to do so. 
• Reduce speed: Drive at moderate speeds and avoid hard acceleration to minimize stress on the engine. 
• Scan for codes: Use an OBD2 scanner to find the specific trouble code. This is the most reliable way to identify the problem. 

This video explains what a flashing check engine light means and what to do: 59sMotoring TVYouTube · Jan 31, 2022
Common causes and solutions

• Faulty ignition coil or spark plug: This is the most common cause, leading to a misfire. 
  • Solution: Inspect and replace the spark plugs and/or ignition coils. It is often recommended to replace all of them at once if one has failed, as the others are likely to follow. 
• Fuel system issues: Problems with fuel injectors, fuel pump, or clogged fuel filter can cause misfires. 
  • Solution: Check the fuel injectors and consider replacing a clogged fuel filter or failing fuel pump. 
• Sensor failures: A bad oxygen sensor or mass airflow (MAF) sensor can cause misfires and other engine problems. 
  • Solution: Replace the faulty sensor as diagnosed by the trouble code. 
• Loose fuel cap: Although less common with a flashing light, a loose or broken fuel cap can trigger a check engine light. 
  • Solution: Check that your fuel cap is tightened securely. If it's damaged, replace it. 

You can watch this video to learn how to replace ignition coils: 1mDanielJaegerFilmsYouTube · Sep 6, 2020
If you are unsure, seek professional help

• Consult a mechanic: If you are not comfortable performing the repairs yourself, take your car to a trusted mechanic for diagnosis and repair. 
• Professional diagnosis: A mechanic can use more advanced diagnostic tools to pinpoint the exact problem, including issues with internal engine components that require specialized tests. 

Can I drive my car with the check engine light blinking?

No, you should not drive a car with a blinking check engine light. A flashing light indicates a serious engine problem, like a misfire, and continuing to drive can cause severe damage to internal engine parts and the catalytic converter. The safest course of action is to pull over as soon as it is safe, turn off the car, and have it towed to a mechanic.
 
This video explains what to do when your check engine light is flashing: 1mproclaimliberty2000YouTube · Dec 13, 2019
Why a blinking light is dangerous

• Severe engine misfire: The most common cause is a misfire, where one or more cylinders fail to ignite the air-fuel mixture correctly. 
• Risk of expensive damage: Driving with a misfire can cause the unburned fuel to enter the exhaust system, which can overheat and damage the catalytic converter, leading to very expensive repairs. 
• Safety concerns: A serious misfire can cause engine hesitation or a lack of power, making the vehicle unsafe to drive. 

What to do immediately

1. Pull over safely: As soon as you can do so without causing a hazard, pull over to the side of the road. 
2. Turn off the engine: Shut off the engine to prevent further damage. 
3. Call for a tow: Do not attempt to drive the car. Have the vehicle towed to a mechanic for diagnosis and repair. 

This video demonstrates how to diagnose and fix a flashing check engine light: 43sArrow GearheadYouTube · Aug 22, 2024

Why does my check engine light flash briefly then go away?

A check engine light that flashes briefly and then goes away indicates a serious issue, most commonly an engine misfire that can cause catalytic converter damage. This temporary problem may be caused by issues like faulty spark plugs, ignition coils, or other engine sensors. While it is now off, you should have the problem diagnosed with an OBD2 scan tool as soon as possible to prevent further damage.
 
Immediate actions

• Reduce speed and avoid heavy acceleration: Drive gently until you can get the car checked. 
• Find a safe place to pull over: If the light returns or other symptoms appear, pull over safely and turn off the engine. 
• Check oil level and engine temperature: Ensure your oil is at the correct level and the engine is not overheating. 

Potential causes

• Engine misfire: This is a very common reason for a flashing light and can be caused by faulty spark plugs, ignition coils, or fuel injectors. 
• Catalytic converter issues: A misfire can lead to the catalytic converter getting damaged, which is an expensive repair. 
• Faulty sensors: Problems with sensors like the oxygen sensor or mass airflow sensor can trigger the light.
• Loose fuel cap: Sometimes, a loose gas cap can cause a check engine light to come on. However, it's less likely to cause a flashing light. 

Next steps

• Get the codes read: The most reliable way to determine the exact problem is to use an OBD2 scanner to read the diagnostic trouble codes (DTCs) stored in the car's computer. 
• Visit a mechanic: A professional can perform a complete diagnosis and repair the underlying issue. Many auto parts stores also offer free code scans.