Why Is My Check Engine Light Flashing And Car Shaking? (10 Reasons Why)

As most drivers know, seeing their check engine light flash on their dashboard can be cause for concern. However, it can be more alarming if their car shakes at the same time.

If your car’s check engine light flashes and your car is shaking, you may want to find out why. We looked up the facts, and here is what we learned!

Why Is My Check Engine Light Flashing And Car Shaking?

1. Faulty Fuel Injectors

Often, a common reason why your car shakes while your check engine light is flashing is that you have faulty fuel injectors.

Fuel injectors can be faulty because they get partially or completely blocked due to dirt, causing the fuel injectors to spray less fuel into the combustion chamber.

Additionally, fuel injectors can be faulty if they are leaky, which can occur if the fuel injector’s O-ring turns hard and breaks from the engine’s heat.

Once the O-ring hardens and breaks, there will be no seal, making the injector fail and causing a drop in the fuel’s pressure.

As such, your car will shake because the car will struggle with the lack of fuel, causing your check engine light to flash.

2. Damaged Idle Air Control Valve

Usually, a car shakes while the check engine light flashes because there is a faulty idle air control valve that leads to not enough air in your car’s cylinders.

Generally, the idle air control valve is in charge of controlling the engine’s idle speed by letting some air pass through the throttle body’s throttle plate.

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Typically, only a small amount of air will be needed to keep the engine running without overwhelming or underwhelming the engine.

However, a bad idle air control valve can make the air entering the throttle body inconsistent, making the engine shake due to misfiring and triggering your check engine light to illuminate.

3. Bad Ignition Coil

Cars tend to shake and have flashing check engine lights because of the engine misfiring, which is often caused by a bad ignition coil.

Usually, ignition coils work like small transformers that make high voltage currents to give power to the spark plug.

However, a bad ignition coil will not be able to produce a high enough voltage, causing your engine to misfire and shake while lacking power, which is why your check engine light turns on.

4. Faulty Spark Plugs

As stated earlier, a bad ignition coil can make your check engine light flash as your car shakes, but so can a spark plug.

If one or several spark plugs are not properly working, it will make your car’s affected cylinder misfire, which makes the car shake and triggers the check engine light.

Usually, spark plugs can work under extreme conditions, so they only become faulty if they get dirty or worn out.

For instance, the engine’s oil or coolant can contaminate the spark plugs, or the spark plugs can become corroded or burnt.

5. Damaged Oxygen Sensor

Damaged Oxygen Sensor

Most modern cars have oxygen sensors that help measure how much unburnt oxygen resides in your car’s exhaust.

However, faulty oxygen sensors can make your check engine light flash and make your car shake.

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If your oxygen sensor is not working correctly, there may be too much or too little oxygen in your exhaust, which can damage other parts of your car.

6. Bad Mass Airflow Sensor

Like the oxygen sensor, a mass airflow sensor calculates the amount of air that goes into your engine, making sure enough oxygen mixes with the car’s fuel.

If the mass airflow sensor is faulty, it will lead to an imbalance in the fuel and oxygen, which will make your car shake and illuminate your check engine light.

7. Faulty Intake Manifold Gasket

Generally, your car has an intake manifold gasket that works as a seal, but if the seal does not work, the engine will overheat.

Normally, this will make your car shake and eventually trigger your check engine light, especially if you ignore the faulty gasket.

8. Broken Engine Mount

Since engine mounts keep your engine in place, a broken engine mount can make your car shake, eventually causing your check engine light to turn on as the shaking leads to engine damage.

9. Fuel Pump

Generally, weak fuel pressure is a common reason why your car would shake while the check engine light flashes.

While you can have weak fuel pressure for various reasons, the weak fuel pressure will trigger your check engine light and make your car shake.

If the fuel pump is faulty, your engine will not be able to maintain combustion because there is not enough fuel in the engine.

Normally, weak fuel pressure can make the engine perform poorly while damaging other parts of the engine.

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10. Clogged Fuel Filters

As stated earlier, weak fuel pressure can be caused by many things, but clogged fuel filters are another common reason why your check engine light flashes as your car shakes.

Usually, clogged fuel filters can make your engine misfire because the cylinder does not have enough fuel pressure.

That said, fuel filters get clogged because the tanks that hold fuel have metallic fragments that can get stuck in your fuel filters.

Normally, your car will struggle to accelerate if the fuel filters are clogged, preventing the correct amount of fuel from reaching the engine.

To know more, you can also read our posts on why your check engine light is flashing, why your check engine light is on Volkswagen, and why cars backfire.


A car shaking with a flashing check engine light means that you have a misfiring issue, such as bad spark plugs and ignition coils.

Additionally, other issues can cause your car to shake and your check engine to light up, including clogged fuel filters, a dirty fuel pump, and faulty fuel injectors.

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