Your car’s dashboard is equipped with many warning lights to tell you when something is wrong. The Check Engine Light might be one of the most recognizable, but most people see it come on as a solid light. In the rare times when the Check Engine Light is flashing, you need to know what to do next.
Throughout this guide, we discuss the main concerns to be aware of when you see a flashing Check Engine Light. We further discuss some steps you can take to resolve the issue.
When you reach the end of our article, you will find answers to your top questions, such as if you should keep driving once the Check Engine Light starts flashing.
What Does a Check Engine Light Mean?
The Check Engine Light indicates that the vehicle’s computer has recognized a fault that needs to be repaired. Issues can range from anything minor, such as a loose gas cap, to problems that are more severe, such as a failing sensor.
The Check Engine Light looks different in different car models. It can come in different colors, like orange, yellow, or red. It also can be a picture of an engine, or have words, such as “Check Engine,” “Service Engine Soon,” or “Check Powertrain.”
Since the 1980s, vehicles have been using an onboard diagnostics system. These systems are responsible for controlling and monitoring performance while regulating engine speed, ignition timing, and the air-fuel mixture. Today, everything is computerized, even to the point of dictating when the automatic transmission shifts.
Solid vs. Flashing Check Engine Light
When the Check Engine Light comes on the dashboard solid (meaning it isn’t blinking), it means there is something that needs to be looked at as soon as possible. In most cases, you would be fine to continue driving home or to the repair shop. However, you don’t want to put off running the codes to see what’s wrong.
On the other hand, if the Check Engine Light starts flashing, there’s a serious issue. You should immediately pull over in a safe location to troubleshoot the car. Do not drive further, or you could cause permanent damage to the engine.
Common Causes Of A Check Engine Light
Some Check Engine Light problems are simple, such as a leaking or loose gas cap. In other cases, it could be due to a bad oxygen sensor, a dirty MAF sensor, intake vacuum leaks, a failing catalytic converter, fouled spark plugs, bad ignition coils, a failing battery or a bad alternator.
Let’s evaluate these possibilities.
1. Loose or Leaking Gas Cap
It may seem strange that a gas cap can cause the Check Engine Light to come on, but it happens often. If the gas cap isn’t sealed completely, it can set a code because of an EVAP leak. This problem occurs if the cap is cracked or you forget to put it on.
Additionally, the code can be set when you fill up with the engine running. Because the computer sees the system open, a code is set. It’s always best to turn off the engine before you open the gas cap. It’s also recommended at the gas pump for your safety.
2. Bad Oxygen Sensor
The oxygen sensor measures the air coming out of the engine to determine how much fuel should be injected. When an oxygen sensor fails, you are going to see the Check Engine Light.
Additionally, there will be a decrease in fuel economy as the air-fuel ratio is imbalanced. It can also create decreased performance. If you don’t replace the oxygen sensor and the car runs rich, you can cause other damage to components such as the spark plugs and catalytic converter.
3. Dirty or Bad MAF Sensor
The mass air flow (MAF) sensor makes up part of the fuel injection system. This sensor measures how much air is entering the engine. It’s also used to determine how much fuel needs to be injected.
For that reason, a failing MAF sensor is going to create a lot of the same symptoms as a bad oxygen sensor. There’s a chance that the sensor is just dirty or contaminated and it can be cleaned up. If so, you save some money on a replacement.
4. Intake Vacuum Leaks
An intake vacuum leak can occur because of several issues. You may have a cracked intake manifold or a faulty manifold gasket.
With a leak, you may hear strange engine sounds, almost like a whistling or hissing. Along with black exhaust smoke, you may deal with backfiring and misfiring too.
5. Failing Catalytic Converter
The catalytic converter is designed to reduce harmful emissions in the atmosphere. Within the converter, catalysts exist to change the composition of the exhaust gas before it hits the air.
When the catalytic converter fails, the Check Engine Light will come on. There may not be any performance issues with a struggling converter, but your vehicle won’t pass an emissions test.
6. Bad Spark Plugs or Ignition Coils
Both the spark plugs and ignition coils are necessary to ignite the air-fuel mixture in the cylinders. Many automakers recommend changing the spark plugs as part of the maintenance schedule, so you can avoid failure.
With either one, you will notice many of the same systems as they fail. The engine may misfire, it will be sluggish to respond and fuel economy will drop.
7. Failing Battery or Alternator
The battery is needed to start the car engine. In relation, the alternator is responsible for charging the car battery while the engine is running.
If the voltage starts to drop, the Check Engine Light is going to come on. You may also get a battery warning light, but this often doesn’t provide a lot of warning before the battery dies.
Batteries often need to be replaced every five years, on average. On the other hand, you shouldn’t need a new alternator as frequently. Most alternators will last seven years or around 150,000 miles.
How To Fix A Check Engine Light
You don’t need to be a mechanic to turn the Check Engine Light off. If you have a compatible scanner and some basic knowledge, you can fix it yourself. Here are some tips to help you out.
1. Read Trouble Codes
With your compatible code scanner, you can read the DTCs to see what’s going on. Plug your scanner into the OBD-II port located under your steering wheel.
If there are a lot of codes present, you may prefer to clear them and restart the car. The light will come back on and set the most prevalent codes for you to research.
2. Research Trouble Code
Trouble codes often have a letter and series of numbers, such as P0100. These trouble codes can be the same across all manufacturers or specific to just one. Some of the trouble codes are going to provide a generic explanation, requiring you to do more research. In this case, you want to use our online trouble code library for more guidance.
If you have several trouble codes showing, you can piece them together to make up a clearer picture. For example, if two codes reveal something wrong with the oxygen sensor, you probably won’t need to do a lot of diagnostics to determine that a sensor is bad.
3. Repair The Issue
Once you know what’s wrong, you can repair it. Of course, fixing the gas cap is easy enough, but some of the other issues may be more complicated.
You can replace the sensor, perform a tune-up with new spark plugs or get a new catalytic converter. Once you get the problem fixed, it’s time to turn off that light.
4. Reset Codes And Test Drive
Now you are ready to plug the scanner back in and reset the codes. Take the car out for a test drive to see if the problem is fixed.
If the light stays off, you are good to go. Otherwise, you might need to move on to the next step.
5. Contact A Professional
If you’ve exhausted your options, it’s time to ask for help. Even as professional mechanics, we sometimes need more support. Search your local area for a qualified mechanic. It’s also helpful to ask for recommendations from the people closest to you.
FAQs
Can I Drive With A Blinking Check Engine Light?
While it might be okay to drive with a solid Check Engine Light, once it starts flashing, it’s time to stop. Continuing to drive could cause irreversible damage to the engine, which is why many cars will also go into a Limp Mode during this time. Pull over on the side of the road as soon as it is safe to do so.
Is It Worse If Your Check Engine Light Is Flashing Or Solid?
It’s never good to see a Check Engine Light. However, the solid warning light is often less troublesome than the flashing light. A blinking Check Engine Light typically indicates imminent failure that could destroy the car engine. For that reason, you should stop driving immediately.
Why Is My Engine Light Flashing And My Car Shaking?
Most of the problems that lead to a Check Engine Light flashing can also cause performance issues, such as shaking. Proper diagnosis will indicate if there’s a spark problem, trouble with the fuel delivery, low pressure or a malfunctioning sensor that is to blame.
Can Bad Spark Plugs Cause Check Engine Light To Blink?
As spark plugs start to foul, the Check Engine Light might not flash. There’s normally time to change the plugs before the problem gets that bad. However, if you let the plugs go unchecked, the engine will eventually misfire, which can cause the Check Engine Light to flash.
How Much Does It Cost To Fix A Flashing Engine Light?
The cost depends on what needs to be repaired. For example, new spark plugs might only cost $100, while low fuel pressure could range anywhere from $50 to $750 to repair. Additionally, malfunctioning sensors tends to cost $50 to $650, while low compression repair can quickly add up to thousands of dollars.
With a flashing Check Engine Light, you know there’s a serious problem that must be dealt with immediately. It could be caused by a misfiring engine or low fuel pressure. It can also be due to a faulty engine sensor or low compression. Either way, you should stop driving immediately.
There’s no room to hesitate because seconds could make the difference as to whether your engine becomes damaged or not. When the light starts to blink, find a safe place to pull over and turn the engine off immediately.
By taking swift action, you have the chance to prevent further damage. With a code scanner or through the help of a professional mechanic, you can figure out what went wrong and begin the repair.