Why is My Check Engine Light Flashing

The check engine light or malfunction indicator lamp in your car is there as part of a warning system that lets you know that there is an issue with the powertrain of your vehicle. The powertrain can be your engine or your transmission.

If you have all-wheel drive, then it can include all-wheel drive element. Basically, all the things that you need to make your car move are considered to be part of the powertrain. Therefore, when the check engine light flashes, these are the systems that are probably affected.

The blinking is a clear sign of danger. Well, most experienced car owners will quickly take their cars for investigation. However, there are others who may not take the matter seriously. In this article, I will tell you why it is not wise to keep on driving with the service light is flashing.

What is a Check Engine Light?

The check engine light, service engine soon, or malfunction indicator lamp is part of your vehicle’s onboard diagnostics system. The system is run by your vehicle’s computer, which is known as the electronic control module (ECM).

What is a Check Engine Light

Nowadays, the electronic control module operates virtually every electronic or electrical system of your vehicle. It also examines out of range operating parameters that are conveyed by the many actuators and sensors, including:

  • Idle speed motor
  • Idle air solenoid
  • Fuel pump
  • Fuel injectors
  • EGR solenoids
  • Canister purge solenoid
  • Air meter sensor
  • Evaporative emission sensor
  • Camshaft and crankshaft sensors
  • Knock sensor
  • Oxygen sensor
  • Engine coolant sensor

For instance, an actuator or a sensor may spot a misfire, unpredictable operation of the fuel pump, unusual output voltage, poor fuel injection, or any other situation that might interfere with the engine emissions or performance.

Usually, the computer system of your vehicle would wait for a few cycles or try to rectify the problem. When the computer is unable to rectify the problem, the on-board diagnostics system will have a diagnostic trouble code stored in the memory, which in turn causes check engine light flashing.

There are basically two types of monitoring that your engine computer does: continuous and non-continuous monitoring.

During continuous monitoring, systems in your vehicle are continuously monitored and checked anytime the engine is on. Some really common ones are engine misfire and engine timing concerns. If something goes wrong with the two, then there can be a serious failure.

When it comes to non-continuous monitoring, your vehicle’s engine computer will run the required tests when the conditions are right. For instance, when your engine computer runs the catalytic converter test, it has to conduct the test when the catalytic converter is at the ideal temperature.

Mostly, your engine computer conducts two-trip monitoring. Generally, it takes two failures before your check engine light will actually come on in your vehicle.

What Does a Blinking Check Engine Light Mean?

If your car’s control system discovers problems that it cannot handle, the check engine light will turn on. In addition, the computer will have trouble code stored in the memory. The code’s main function is to determine the origin of the problem.

To read the code, you will need a diagnostic computer or an electronic scan tool. There are also several low-priced code readers on the market for DIY. Typically, the code will only direct you towards the problem, but you will need an expert to do a full diagnosis and repair.

Intermittent, Continuous Illumination or Continuous Flashing

The check engine light blinking then goes off, the condition is referred to as soft failure or intermittent. This problem usually occurs when there is a specific condition, such as a broken wire, which connects and disconnects, causing the light to go on and off.

Continuous illumination occurs when the light turns on and stays illuminated. Normally, this indicates a hard failure. For instance, a dirty mass airflow sensor may cause the light to continue to illuminate until you replace or clean the sensor.

If the check engine light is steady, the issue may not be an emergency. Modern vehicles are very advanced, so you may not experience deterioration in performance. However, I suggest you schedule an appointment with an automotive mechanic as soon as possible.

When the service engine light flashing is continuous, then you have a serious problem that can lead to grave damages if the problem is not addressed. In most cases, a misfire can cause the light to flash continuously.

Check Engine Light Flashing and Car Shaking

Check engine light flashing car shaking is a clear sign of trouble. Vibration or shaking may be caused by misfires, poor fuel pressure, or faulty spark plugs. You should also know that a defective idle air control valve might make the engine idle drop significantly.

This may cause the motor to vibrate or shake abnormally. This can lead to a loss of power that vibrates all over the motor, leading to other issues, such as fuel timing and ignition. A misfire always develops a disproportion in the motor, causing vibration or shaking.

Another issue that may cause check engine light blinking car shaking is a broken engine mount. Basically, engine mounts are rubber mounted props that grip the engine into position to the chassis of the vehicle. If the mounts weaken or break, heavy vibration or shaking will be experienced.

If you experience, check engine light flashing and car vibrating, I would strongly recommend you to have an expert inspect and diagnose your vehicle.

What Should I Do When My Check Engine Light Is Flashing?

You have a number of options. You can take your car to your local dealership, and have them do a full diagnosis. Usually, dealerships have extensive knowledge of vehicles. For example, Chevy Cobalt knows their cars very well; so, that is a great option.

There are also many independent shops that specialize in different brands, maybe the brand of your car including Acura, Chevy, Dodge, Ford, Honda, Hummer, Jeep, Nissan, Subaru, Toyota, GMC, etc. You can even take your car to such shops for a full diagnosis. The third option that you can settle for is buying your own OBD-II scanner and conducting a DIY.

With each of these options come some advantages and disadvantages. If you take your car to a dealership or an independent shop, odds are you are going to be charged a diagnostic fee. The good thing is that they will have all the info and equipment needed for proper diagnosis.

Using your own OBD-II scanner, you may save money in the diagnostic process. However, you might not have all the repair and all the diagnostic information. You may also lack the test equipment for properly pinpointing the problem with your car.

In Conclusion

You should always find out the reason behind your check engine light flashing. If you are well-informed, then self-diagnosis is a great option. The self-diagnostic systems of nowadays are very advanced, and they do more than typical monitoring operations.

However, if you have little or no knowledge of engine problems, then I strongly urge you to seek the help of a professional. You can get the appropriate services from dealerships and independent shops.

Jack Harris

Jack Harris is a talented and advanced author, blogger, auto expert and senior technical consultant with Autosneed. He is a mechanical engineer who holds a Machine Lubricant Analyst (MLA) Level III certification and a Machine Lubrication Technician (MLT) Level II certification through the International Council for Machinery Lubrication (ICML) and ASE Certified. After years of working as both an automotive journalist and a Ford factory technician, to say I live and breathe the automotive world could still be considered an understatement.

34 thoughts on “Why is My Check Engine Light Flashing”

  1. Thanks so much for this blog, very helpful. We took our car to an independent shops and did diagnostics but told us they couldn’t find any code showing up in their computer and can’t find the problem. So now we just wasted over $100 for diagnostic that really did not give us anything. We were told to bring the car to a car dealership. Do you think the dealership would know fully? Thanks for advice.

      • When I go 50 and up my car starts vibrating in the engine light is blinking And sometimes it stays on I feel like is rattling as if though the tires are flat that’s the noise that it’s making

    • My car was running great. Then I took it into the shop and had the oil changed. Now, my check engine light won’t go off and I went to go to the store. My car has no power and and is shaking. I went around the block and came home. It’s a Honda V6. Any ideas?

  2. My engine light is blinking but then stops after a few minutes. As soon as I press on the gas to start moving my car starts vibrating all over. Takes about a good minute to get passed 20mph. Any advice?

    • Hi Trevor.

      The job of the obd scanner is to provide the exact problem by showing you a code. Use a scanner tool to get the error code as soon as possible. When your vehicle is running, the alternator takes over the job of supplying power. Due to this fact, I doubt that the battery can the cause of the lack of acceleration problems. I would suspect that, this is caused either by a faulty sensor or an ignition / fuel system component which is dirty, has a bad electrical connection or is damaged and requires replacement. It’s better to have a professional come to your location to complete a car is slow to accelerate inspection to determine the source of this problem.

        • Possible problems:

          • Vacuum leak
          • Transmission problem
          • Battery sensor

          It’s better if you can find out the check engine error code. Problem can be solved easily. Otherwise take it a nearest workshop.

        • Hello.
          I have a problem with the car not carrying properly mainly in elevations. The fault code is 1405 egr sensor When I replaced a new sensor the vehicle was shaking while stopping, I checked a vacuum escape with a spray and did not find the problem.

          Ford Taurus 3.0L 2001.

  3. My name is jay I have a 2001 grand marquis mercury and it’s giving me problems when I drive it the car starts shaking/vibrating the check engine light flashes for a few minutes then it stops and it starts all over again

      • I have a VW 2.8 that the cam tensioner pad had broken up and clogged my oil pumps screen. After replacing pad that’s a plastic fiber and getting motor flushed. I put things back together only to find my motor won’t ifle and won’t take gas stalls sometimes. After it gets going it runs ok but no power. I have P0300, po302, 302, 303 with cam sensor fault etc. I think it’s a jump in timeing from the pad replacement.

  4. having the same problems as almost all of the above. Had new computer installed, had new altinator installed. I should drive a car is not shaking with the light on, must put miles on the new computer In 50-100 miles! How can I drive the car 5t0-100 miles with it shaking like this and light on???????? I am afraid of car stopping or shutting down on some back road and need a tow!!! Is this good to do?? I can not push it I am 83 yeARS OLD!!!!! dIMY FIRST TIMED NOT LEAVE THIS BEFORE…

  5. 2008 Hyundai Sonata. only does it a few times then it’ll stop shaking. and then a couple hours later it will start shaking again. any help will be appreciated

  6. Hello,
    I have a 2003 VW Passat. This morning, my car was shaking and the engine light was blinking. It started when I approached a stop and briefly while I was stopped. Then everything seemed to go back to normal. You mention poor fuel pressure and I wonder if this could be due to the cold. We had below 0 temps and maybe my gas line started to freeze. I just got this car in the summer, so I’m still figuring out how it does in MN winter!
    Thanks, Anni

  7. I have Audi A4 3.2 My engine light is Flashing and car is shaking but then stops after 5 to 10 minutes driving.But engine light has been on for a while. Any advice.

  8. I was having a problem with my antifrezz light coming on my mecanhic said i had a leak from my lower radiator hose so while we were waiting to get the hose i was still driving the car and it was running ok then this morning when i started it up the low antifrezz light came on again so i went to store and got some antifrezz and put it in the antifrezz container on the way home my car started to sudder and shake i drove home doing about 20 miles per hour i sat in my driveway with the car on and it continued to shake and run rough what should i do?

  9. Hi my check light engine is blinking and the car is shaking. When I press accelerator it shakes more, any suggestions on what it could be?

    • Engine mounts cause front end to shake or vibrations and sounds when driving over a bunb also makes engine light to come on to stay on or it blinks .

  10. I have a ford f 150 5.4l . I was told my truck is misfiring and my o2 sensor maybe bad. And that is why my truck shakes really badly. Not sure yet haven’t had money to get it looked at.

  11. Hi i have a GWM Florida VVT 1.5 my check light engine is blinking and the car is shaking. When I press accelerator it shakes more and make a terrible noise , any suggestions on what it could be.

    Thanks in advance

  12. Hi Jack.
    Thank you for your expert and detailed advice; your in-depth knowledge is impressive.

    I’m trying to assist my mother in diagnosing a slight problem she has recently picked up on her Renault Sandero Stepway 2013 1.6. When she drives the check engine light remains illuminated and she has experienced a slight vibration and subtle and unusual noise in the vehicle.

    Any possible suggestions what these signs might be leaning towards?

    Lindsey- South Africa

    • Hi Lindsey,

      Hope you’re doing great. This can happen for many different reasons. If your vehicle’s computer detects any issues, Check Engine Light will come on and indicate the issue. In this COVID 19 situation, I would suggest having a local expert, diagnose and inspect your vehicle.

      Stay safe!

    • I have a 2007 Dodge Caliber, it was shaking and the check engine light been on but now it is flashing. Please help as soon as possible

  13. My 2002 Toyota Camry started to experience the CEL flashing and car shaking combo today. It only happens when the car is in idle though, mainly with my foot on the brakes. When i drive or even parked there’s little to no shaking and if I recall the light wasn’t flashing. But when I was idling on the brakes, like at a red light, stop sign, parking lot or intersection is when it began to shake and the light flash. I only drove for less than a mile after this. Any idea what the issues could be specifically? I absolutely am going to take it to my mechanic. My main question is, is it safe to drive my car to my mechanic who is 10 miles away, which includes highway driving?

  14. I have a four-wheel-drive Xterra. It is not driven a lot. Once in a while when I get in it it acts like it’s not cheating at all it’s soldiers and shakes a little bit. After going a few blocks and it warms up it’s OK. But the check engine light had not been coming on. Last week I drove it to the mountains When I went to start it in the morning yes I was coming out was not steady shaking A little. After driving it just a few blocks quit shaking and I came to a roadblock and had to sit for 15 minutes. When I started up the check engine light came on and flashed 20 or 30 times. And the light went off and did he come on again. The next day I was on the highway close to home and it just felt funny like the tires weren’t totally inflated or I can’t really explain it but it wasn’t just right after a little bit it went away. I drove him to the dealership they were so many codes in it that their devices would read the current code so all the codes are stripped out. The hope is that the next time it does it I can get it to the dealership and they can read the code because there will be no other Stored codes. Any suggestions would be appreciated. It’s an old car 2000 four-wheel-drive Xterra over 200,000 miles.


Leave a Comment