Blog Car Care Advice Check Engine Light Flashes Then Goes Off: 7 Reasons (+Fixes)
Car Care Advice

Check Engine Light Flashes Then Goes Off: 7 Reasons (+Fixes)

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What does it mean when your check engine light flashes then goes off?
A flashing check engine light that goes off can indicate issues, like an engine misfire or temporary engine sensor glitches.

What should you do about it?

We’ll explore what could cause the check engine light to flash on and off and answer some related concerns. 

This Article Contains:

Let’s go!

What Does it Mean When Your Check Engine Light Flashes Then Goes Off?

The check engine dashboard light comes on as a solid light when the car’s Engine Control Module (ECM) notices odd engine sensor readings, indicating potential engine problems. It may not require immediate attention, but you should get your vehicle checked sooner than later. 

On the other hand, a flashing CEL could come on due to severe problems like engine misfires, O2 sensor malfunction, catalytic converter issues, and more. 

In either case, if the light turns off on its own, it might have been an intermittent problem like sensor glitches or temporary electrical faults in your car. But if the CEL continues flashing intermittently, you must take your car to a mechanic ASAP. 

Let’s explore the reasons behind a CEL that flashes and goes off.

7 Worrying Reasons Your Check Engine Light Flashes Then Goes Off 

Here’s what may cause a check engine light to flash and then go off:

1. Engine Misfires

A check engine light that flashes intermittently is often due to an engine misfire, where one or more cylinders fail to ignite the air-fuel mixture correctly. This can affect the engine performance due to unburned fuel. 

Common causes of engine misfires include: 

The illuminated check engine light may go off after the engine stabilizes.

2. Malfunctioning Oxygen Sensors

The oxygen sensor measures unburnt oxygen in the exhaust system and aids your car’s computer in maintaining an ideal fuel mixture. 

When the oxygen sensor fails to provide accurate data about the air-fuel mixture, the ECM may receive incorrect information, leading to the intermittent flashing of the check engine light.

3. Damaged or Loose Gas Cap

A damaged or loose gas cap might cause the check engine light to come on briefly as it allows air to enter the fuel system. 

However, the light will turn off when the ECM realizes that the gas cap isn’t letting in enough air to impact the air-fuel ratio.

4. Defective Mass Air Flow Sensors (MAF)

The MAF sensor measures the air entering the engine. The ECM uses this data to adjust the fuel injection for optimal combustion.

A faulty MAF sensor can trigger the check engine light due to incorrect readings, impacting the air-fuel ratio and emissions. If the emissions are high temporarily, the check engine light comes on and goes off once the condition returns to normal.

5. Broken Thermostat Valves

The thermostat regulates the coolant flow to maintain the right engine temperature.

If the thermostat is broken or stuck, the engine can overheat and activate the check engine light. The light may turn off when the engine cools down or the issue resolves itself. 

6. Catalytic Converter Issues 

The catalytic converter reduces harmful toxic emissions and converts them into less harmful gasses. 

A clogged or failing catalytic converter can lead to a build-up of toxic fumes in the exhaust system, resulting in inaccurate readings and disruptions in the emission control system. This can trigger the check engine light to flash intermittently. 

7. Faulty Exhaust Gas Recirculation (EGR) System

A faulty Exhaust Gas Recirculation (EGR) system can cause the check engine light to flash and go off due to irregularities in the recirculation of exhaust gasses. 

When the EGR system gets clogged with dirt and soot in the valves, it increases emissions and leads to improper combustion, temporarily illuminating the check engine light.

Next, let’s see what to do about a flashing CEL. 

How to Fix and Reset a Flashing Check Engine Light?

To reset a flashing engine light, you need to fix the underlying issue.
Here are the steps a mechanic would take during check engine light service:

  1. They’ll use an OBD II scanner to retrieve the check engine light codes. These error codes indicate what’s causing the blinking light.
  1. Based on the code, they’ll:
    • Fix worn or damaged spark plugs, plug wires, or ignition system components.
    • Fix any malfunctioning sensors.
    • Address problems with the fuel system or the exhaust system.
  1. They’ll use the OBD II scanner to reset the check engine light codes and take the vehicle for a test drive.
  1. If the light is still on, they’ll turn off the engine and restart it after three to five minutes to ensure the reset is successful.

Want to know how much a check engine light service can cost?
Keep reading!

How Much Does Check Engine Light Repair Cost?

Diagnosing a check engine light on your car can cost around $88 to $144. 

Additionally, here are the estimates for some standard CEL replacement services you may have to undertake:

Got more check engine light questions?
Check out these FAQs. 

3 FAQs about a Flashing Check Engine Light

Here are answers to some commonly asked questions about an illuminated check engine light. 

1. Can You Continue Driving if Your Check Engine Light Flashes?

​​No. Driving with a check engine light that flashes and goes off is unsafe. It indicates critical engine problems such as a misfire that can irreversibly damage your vehicle.

Ignoring a blinking check engine light can also harm vital components like the catalytic converter, resulting in expensive repairs.

So, if you notice a blinking light, it’s best to pull over and tow your car to an auto repair shop.

2. Why Does Your Car Shake When the Check Engine Light Is Flashing?

Your car shaking when the check engine light flashes can be due to an engine misfire triggered by a damaged ignition coil or spark plug wire.

You should pull over at a safe spot to prevent further damage and get your car checked ASAP.

3. Is a Flashing Engine Light Worse than a Solid Check Engine Light?

A flashing light indicates a severe problem, such as a misfire, that affects your engine performance and needs immediate attention. In contrast, a solid check engine light indicates minor engine problems that don’t need to be addressed urgently, but still require your attention.

Either way, it’s best to get a solid or flashing light addressed promptly by a professional to avoid engine problems.

Fix Check Engine Light Issues with AutoNation Mobile Service

A flashing check engine light often points to an engine misfire or problems in the emissions system that need immediate attention. Diagnosing this issue can be tricky, and repairs are usually complicated.

Fortunately, that’s where AutoNation Mobile Service can help.
We’re a mobile auto repair and maintenance service offering upfront pricing and stellar customer service

Contact us to have our experts resolve your check engine light issues in your driveway.