Many warning lights on your car’s dashboard are there to let you know when something is wrong. The Check Engine Light might be one of the most known warning lights.
However, most people see it come on as a solid light, and only a few times do you see the Check Engine Light flash. If you should ever encounter a flashing Check Engine Light, it is important to know what steps to take next.
In this guide, we will discuss the main things to keep in mind when you have a flashing check engine light, as well as some solutions you can try to fix the problems the Check Engine Light is indicating.
At the end of our article, we will answer some of the most common questions you might have, such as whether or not you should continue to drive a car that has a flashing check engine light.
What Does the Check Engine Light Mean?
The Check Engine Light shows the vehicle’s computer stored a fault it needs repaired. The fix could be anything from minor (like a loose gas cap) to major (like a failing sensor).
The Check Engine light looks different in different makes and models of cars. It can be different colors: orange, yellow or red. It can picture the engine, it can have the words, “Check Engine,” “Service Engine Soon,” or “Check Powertrain.”
Since the 1980s, vehicle manufacturers have incorporated onboard diagnostics. The onboard diagnostics system controls and monitors performance by regulating ignition timing, engine speed and air-fuel mixture.
Most vehicle systems are now at least somewhat computerized, including automatic transmission shifting management.
What does a check engine light look like?
Solid vs. Flashing Check Engine Light
When the Check Engine Light appears solid (doesn’t blink) on the dashboard it indicates something that needs attention as soon as possible. You would usually probably be okay to keep driving (without causing damage) until getting home or to a repair shop, but it’s best to not delay in running the codes to find out the issue.
If the Check Engine Light starts FLASHING however, there’s a problem. Stop driving immediately and pull over to a safe area to troubleshoot the car. If the light is flashing, you may cause permanent engine damage by driving the car any further.
Why is My Check Engine Light Flashing?
When a flashing check engine light, it likely indicates a much worse condition. In most cases, a flashing light means that the engine has a misfire and unburned fuel is entering the exhaust system.
As a result, the temperature of the catalytic converter can be raised excessively leading to possible serious damage. If you notice a flashing check engine light, it is best to pull over immediately and turn off the engine, as soon as it’s safe to do so.
A flashing light, or fellow users may refer it as a red light instead of a yellow or orange light, means something is wrong and should be treated as an emergency. You should pull over, turn the engine off and have a mechanic check it out.
As a thumb rule in most new cars, directly correlated to a flashing check engine light is an engine misfire severe enough to dump unburned fuel into the exhaust, which can quickly damage the catalytic convertor leading to a costly repair if continued to operate the vehicle. In this situation you should disengage power and have the vehicle looked at as soon as possible.
If steady light, the condition generally is not an immediate emergency, but should still be attended to as soon as possible!
Common Causes Of A Check Engine Light
There are some Check Engine Light troubles that are easy fixers, such as a leaking gas cap or one that is loose.
In these other cases, it could be a result of a bad oxygen sensor, dirty mass airflow (MAF) sensor, intake vacuum leak, failing catalytic converter, fouled spark plugs, bad ignition coils, a bad battery, or failing alternator.
Let’s look at these possible problems.
#1. Loose or Leaking Gas Cap.
It may seem odd that something as simple as a gas cap can caused a Check Engine Light, but it actually occurs frequently. If the cap is not completely sealed, it could set a code for an EVAP leak. This happens if your cap is cracked or forgot to put it back on.
Furthermore, you can have a code set when you fill up with the engine running. The computer sees that the system is open, and will set a code. Always turn off the engine before opening the gas cap, and it is recommended to turn the engine off at the gas station for your safety.
#2. Bad Oxygen Sensor.
The oxygen sensor reads the air that is coming out of the engine to know how much fuel to inject. When an oxygen sensor fails, you are going to see the Check Engine Light.
In addition, you will have poorer fuel economy as the air fuel ratio will be incorrect. It can also result in less performance. If you do not replace the oxygen sensor and the car continues to run rich, it can impact other components damaging the spark plugs and catalytic converter.
#3. Dirty or Bad MAF Sensor.
The mass air flow (MAF) sensor is part of the fuel injection system. The MAF sensor measures how much air is going in to the engine. For that reason, it is also used to determine how much fuel needs to be injected.
So, a MAF failing is going to cause a lot of the same symptoms as a bad oxygen sensor. There is a possibility that the MAF is just dirty or contaminated, and it can be cleaned up and save money not needing a replacement.
#4. Intake Vacuum Leaks.
Intake vacuum leaks can arise from multiple sources. You might have a cracked intake manifold or a bad manifold gasket.
When you do have a leak, you will hear weird engine noises — often close to a whistling or hissing noise. In addition to black smoke from the exhaust, you may be dealing with misfiring and backfiring, too.
#5. Failing Catalytic Converter.
Catalytic converters are in the vehicle to reduce pollutants in the atmosphere. Catalysts inside the catalytic converter are changing the exhaust gas’s composition before the exhaust gas leaves the vehicle.
When the catalytic converter is failing, the check engine light will turn on. You may not have performance issues occurring with a failing catalytic converter; however, your vehicle is less likely to pass an emissions inspection.
#6. Bad Spark Plugs or Ignition Coils.
Spark plugs and ignition coil/deck coils are both necessary to ignite the air-fuel mixture in the cylinders. Many vehicle manufacturers recommend changing the spark plug on maintenance schedules, so at least you can work to avoid failure.
You’re going to notice many of the same symptoms in failure for either the plug or ignition coil. Your vehicle is going to be misfiring, engine response is going to be sluggish, and you’re fuel consumption will be lower.
#7. Failing Battery or Alternator.
Batteries are needed to start the vehicle engine, and a battery system is charged by the alternator, while the vehicle engine is running.
Dropping voltage is going to cause your warning light will illuminate. You may also receive a battery warning light but don’t think that gives you a lot of warning before the battery dies.
Batteries last on average around five years. Alternators generally have longer lifespan; on average seven years or the first 150,000 miles.
How To Turn Off A Check Engine Light
You don’t need to be a mechanic to turn off the check engine light. If you have a suitable scanner and a little know-how, you may be able to fix it yourself. Here are some tips to help you.
#1. Read the Trouble Codes.
With your suitable code scanner, you can read the DTCs, to find out what’s going on. Plug your scanner into the OBD-II port located under your steering wheel.
If you have a lot of codes present, you might prefer to clear them all, and restart the car, and the light will come back on with the most relevant codes for you to research.
#2. Research the Trouble Codes.
Trouble codes usually consist of a letter and series of numbers, like P0100. These trouble codes can either have the same meaning across all manufacturers, or be unique to one. Some of the trouble codes will give you a generic explanation, and others you will need to do more research on. In this situation, you want to check out our online trouble code library.
If you have several trouble codes showing, you can piece them together for a clearer picture. For example, if two codes suggest something is wrong with the oxygen sensor, you probably don’t need to go through a lot of diagnostics to determine that the oxygen sensor is bad.
#3. Fix the Problem.
Once you know what is wrong, you can fix it. Certainly, the gas cap is simple enough, but some of these problems can be more drawn out.
You can either replace the sensor, do a tune up with a new set of spark plugs, or install a new converter. Once you resolve the issue, you are ready to turn off that light.
#4. Reset Codes and Test Drive.
Now you are ready to plug in the scanner and reset the codes. Test drive your car and see if the issue is fixed.
If the light remains off, great. If there is an issue or the light reactivates, you may need to move to the next option.
#5. Ask for Help.
If you have gone through everything, consider getting help. Even us pro mechanics ask for a second or third opinion from time to time! Search your neighborhood for a qualified mechanic. While inquiring, it might also help to ask friends and family for a recommendation.
How Long Can You Drive with Check Engine Light On?
Typically, you should only drive with the Check Engine light on between 50 and 100 miles before at least scanning the computer for error codes.
Some vehicles may have issues related to the sensors on the vehicle—driving for a short period allows time for the sensors to recalibrate or reset which could possibly turn off the Check Engine light.
If the light stays on after driving for a while, scan the engine computer to determine WHAT the issue is—after that the decision is yours as to whether you will fix the issue now, or continue driving with the light illuminated.
Ultimately, how long you can drive with the Check Engine light comes down to your attitude towards fixing the issue.
Note: If your Check Engine light turns on, get the engine computer scanned for error codes as soon as you can to determine the issue. Once the issue is diagnosed you can make the decision of how long you wish to drive with the light illuminated.
What to Do About a Check Engine Light?
Since you’ve chosen not to ignore your check engine light, you can bring your car to a shop to assess what is going on. Or, you can assess it yourself.
Fix recommends that you purchase a pocket scan tool – they are able to work with cars made 1996 and onward. Referred to as ODB-II or “on-board diagnostics second generation,” the scan tool will read your car’s diagnostic trouble codes automatically. You can obtain a scan tool online or at auto parts stores for a metered $50.
“You can plug the scan tool into the OBD II port, a 16-pin connector under the dash,” says Fix. “If you get a code, write it down.” Then look in your owner’s manual for what needs fixing – or before you take it in for service.
FAQs.
Can I Drive with A Flashing Check Engine Light?
If you have a solid Check Engine Light you probably could drive the vehicle, but if that light is blinking, you should stop driving.
Continuing to drive will likely cause catastrophic engine issues. This is why many vehicles will even enter into a Limp Mode. If you have to stop, pull over to the side of the road safely as soon as you are able.
Is It Worse If Your Check Engine Light Is Flashing or Solid?
There’s never a good time to see a Check Engine Light illuminated on your dash, but usually a solid light indicates a less severe problem than a blinking light.
A flashing Check Engine Light usually indicates an instant failure is occurring which will cause destruction of the car engine. For that reason, you should pull over at the safest opportunity.
Why Is My Engine Light Blinking and Car Shaking?
A lot of the issues leading to a Check Engine Light blinking in your dashboard could also create other issues, such as shaking. A proper diagnosis will reveal whether it relates to a spark issue, fuel delivery problem, low fuel pressure, or a compromised sensor.
Can Bad Spark Plugs Cause Check Engine Light to Blink?
In most cases when spark plugs start to foul out, the Check Engine Light is not flashing. There is usually time to replace spark plugs before it gets to that point, but if you let your engine go unchecked eventually it will misfire which will cause the Check Engine Light to illuminate or blink.
How Much is It cost to Fix a Blinking Engine Light?
Cost will depend on what the repair entails. For example, spark plugs might only run you around $100, where as a low fuel pressure repair might be $50-$750. A bad sensor often ranges between $50-$650 and low compression repair could run into the thousands fairly quickly.
If you have a blinking Check Engine Light you know that there’s a significant issue that needs to be addressed on the spot. That issue could consist of a misfiring engine, low fuel pressure, malfunctioning engine sensor, or low compression. Either way, you should not continue to drive your vehicle.
There is no sense of pause as seconds can determine whether or not you end up damaging your engine during a blinking Check Engine Light condition. Immediately when the light starts to blink, look for a safe place to pull over and turn the engine off.
Performing this quick action gives you the best chance of prevent further damage to your engine. If you have your own code scanner or have access to a mechanic, you can be advised of the potential issue and begin repairs.