Why Is the Check Engine Light Flashing And Car Shaking?


Suppose you find your vehicle shaking when you drive or when sitting at the idling of the traffic lights. When you have a check engine light flashing and car bouncing, then you can’t deny that there may be a problem with the engine. 

This particular problem might lie because of the faulty ignition coil, fuel supply, or spark plugs. When such a problem occurs, it is better not to drive the vehicle, as it can be an engine fault sign that you should lookout.

What are the main reasons for car shaking and a flashing check engine light?

  • A bad fuel injector


This is a pervasive engine problem that can cause the engine to shake and flash the check engine light. Direct injection is the technique used in modern engines for getting the fuel into the cylinder. It can be blocked if the nozzle or the tip becomes dirty and shutting off the engine causes the injector to stay hot for long and leave behind the hydrocarbon deposits.

How To Clean The Injector?

If you think that your check engine light flashing is caused by the dirty injector, you can try to solve it by simply cleaning it. Cleaning the injector is a simple process that can be done at home with some basic supplies. You will need:

-A can of compressed air;

-A clean, lint-free cloth;

-Rubbing alcohol;

-A small brush (optional).


1. Begin by disconnecting the power to the injector.

2. Next, use the compressed air to blow any dirt or debris out of the injector.

3. Once the injector is clean, soak a lint-free cloth in rubbing alcohol and use it to wipe down the exterior of the injector.

4. If there is any stubborn dirt or grime, you can use a small brush to lightly scrub it away.

5. Allow the injector to air dry completely before reconnecting the power and using it again.

If you cleaned your injector but your car keeps shaking, maybe it's time to change your fuel injector. If your car's injectors are going bad, you'll need to replace them. This is a fairly straightforward process, but it's best to have a professional do it. They'll have the right tools and expertise to make sure the job is done properly.

  • Blocked fuel filter


A common reason for the car shakes is the engine misfire, which happens when the accelerator is pushed on. This is usually caused by the lack of fuel pressure in the cylinder, while sometimes, it is also caused by the blocked fuel filter that has not been changed on time.

How To Change The Fuel Filter On Your Car?

Car fuel filters need to be changed regularly in order to keep your car running properly. Moreover, a dirty fuel filter may be one of the major problems that cause check engine flashing and car shaking, so if this problem has occurred to you - try this method! Depending on your car's make and model, the frequency with which you need to change your fuel filter will vary. However, it is generally recommended that you change your fuel filter every 10,000 miles or so.

When you are ready to change your car's fuel filter, follow these steps:

1. Locate the fuel filter. In most cars, the fuel filter is located somewhere along the fuel line, often near the fuel tank or under the hood. Consult your car's owners manual if you are unsure of where to find the fuel filter.

2. Disconnect the negative battery terminal. This will help to prevent any sparks from occurring when you are working on the fuel system.

3. Relieve the pressure in the fuel system. Before you can remove the fuel filter, you need to release the pressure in the fuel system. To do this, locate the fuel pump fuse in the fuse box and remove it. Then, start the car and let it run until it stalls.

4. Disconnect the fuel lines. Once the pressure has been relieved, you can disconnect the fuel lines from the filter. Be sure to label the fuel lines so that you know which one goes where when you reconnect them.

5. Remove the old fuel filter. With the fuel lines disconnected, you can now remove the old fuel filter. Simply unscrew it from its location and discard it.

6. Install the new fuel filter. To install the new fuel filter, simply screw it into place and reconnect the fuel lines.

7. Start the car and check for leaks. Once you have installed the new fuel filter, start the car and check for any leaks. If there are no leaks, you can now reinstall the fuel pump fuse.

8. Take the car for a test drive. Finally, take the car out for a spin to make sure that everything is working properly. If all goes well, you've successfully changed your car's fuel filter!

  • A worn-out ignition coil


Bad coil packs or ignition coils are the leading causes of check engine flashing lights and car shaking. These engine oils are mini transformers generating a high voltage current powering the spark plug. The significant symptoms of the lousy ignition coil are a rough engine idle, engine misfires, a poor fuel economy, and a decrease in power.

How To Change The Ignition Coil?

Assuming that you have all of the necessary tools, the process of changing the ignition coil is actually quite simple. Here are the basic steps:

1. Disconnect the negative battery cable.

2. Disconnect the spark plug wires from the coil.

3. Unscrew and remove the coil from its mount.

4. Install the new coil in the mount and screw it in place.

5. Reconnect the spark plug wires.

6. Reconnect the negative battery cable.

And that's all there is to it! Just remember to never work on a car's electrical system with the engine running, as you could seriously injure yourself. We hope that after these actions your check engine will stop flashing.

  • A worn-out spark plug


Worn-out spark plugs can cause your engine to misfire, run less efficiently, and produce less power. Moreover, you will have check engine flashing on a dashboard if your spark plugs are showing signs of malfunction. You may also notice that your vehicle runs rougher than usual when you have worn-out spark plugs. It is therefore important to replace your spark plugs as soon as they become worn-out.

How To Change Spark Plugs On Your Car

Most people don't think about changing their spark plugs until their car starts acting up. But, like all other parts of your car, they eventually wear out and need to be replaced. Follow these steps to change the spark plugs on your car.

1. Locate the spark plugs. They're usually located at the top of the engine, near the front.

2. Using a ratchet and spark plug socket, remove the old plugs.

3. Inspect the plugs for wear and tear. If they're damaged, you'll need to replace them.

4. Gap the new plugs using a feeler gauge. This ensures that they'll fire properly.

5. Install the new plugs, hand-tightening them until their snug.

6. Use the ratchet to tighten the plugs for another quarter turn.

7. Reconnect the spark plug wires to the new plugs.

8. Start the engine and listen for any strange noises. If everything sounds normal, you're all set!

If your car shaking and checking engine flashing even after this operation, consult a mechanic. There could be another issue at play.

  • A bad idle air control valve


This can be one of the major causes for the car to shake because of the lack of air getting into the cylinders. The idle air valve happens to control the engine’s idle speed, thus allowing air flue to pass around the throttle plate, and uses the built-in conduit on the body of the throttle.

How To Fix a Bad Idle Air Control Valve

If your idle air control valve is going bad, there are a few things you can do to try and fix it. First, check the vacuum lines that go to the IACV. If they are cracked or leaking, they will need to be replaced. Next, clean the IACV with carburetor cleaner. If this does not fix the problem, you may need to replace the IACV.

How do you fix check engine light flashing and car shaking?

  • If you find the error code pointing to a problem with the fuel pressure, you need to begin by changing the filter and checking for any leaks or blockages in the fuel system.
  • It would be best to remember that the bad idle air-controlled valve can easily be identified by how your vehicle is moving. This is usually an error code of P0505, and you can resolve this issue by making different tests for the IAC.
  • A specific error code appears because of the failed engine sensor. This issue can be resolved by clearing the trouble code or changing the offending sensor.

Bottom Line

Some of the main reasons for checking engine light flashing and car shaking can be worn-out coils, faulty spark plugs, or a leaking gasket. It is better to observe the dashboard lights regularly and note the symbols in different colors. When the characters appear in blue, white, and green lights, you don't need to worry. However, if the yellow and red lights appear, it is better to take the vehicle for a checkup.