6 Reasons Your Check Engine Light Flashes and Your Car Shakes
For the average driver, there are few situations more stressful than suddenly noticing that your car has started shaking violently while your new check engine light is on. Learn about the various causes of vehicle shaking accompanied by a flashing check engine light and whether it is safe to continue driving.
Check for a Flashing vs. Constantly Lit Engine Light
In general, there are two different types of check engine lights, the first being a constant-on check engine light. The second type is one that flashes repeatedly at a set pace.
In most cases, the latter of these two types of engine check lights indicates that a more serious problem is currently underway. This message is usually regarding a current misfire detected in one or more specific cylinders.
What Causes Car Shaking When Check Engine Light Blinks In most cases, a flashing Check Engine Light accompanied by noticeable shaking is a sure sign of a cylinder misfire. While it’s rarely hard to pinpoint a misfire as the root cause of the symptoms listed above, it’s generally much harder to pinpoint the cause of the misfire itself.
Here are some of the most common causes of cylinder misfires:
#1 – Faulty/Damaged/Fouled Spark Plugs
Your engine’s spark plugs are responsible for providing each cylinder with the spark it needs to start combustion.
Over time, spark plugs can become fouled or improperly gapped, making them difficult or unable to ignite. This causes a misfire, which can only be fixed with proper maintenance. Checking the condition of your spark plugs (and replacing them if necessary) can help prevent future misfires.
#2 – Damaged Ignition Coil/Spark Plug Wires
Ignition power is delivered to the cylinder’s spark plugs via special spark plug wires or special ignition coils (for engines with coil-on-spark plug ignition systems).
Over time, and when exposed to the heat generated by the engine, the insulated outer casings of these components can become brittle and crack, causing ignition power to reach the ground prematurely.
#3 – Damaged/corrosive distributor cap or faulty ignition coil
Another possible cause of active misfires is a partial failure of the engine’s distributor cap or ignition coil.
Many older internal combustion engines used such devices to time the spark delivery to each cylinder. Unfortunately, distributor caps were prone to cracking and corrosion, and coils frequently suffered from heat-related failures.
#4 – Fuel Delivery Issues
Another common cause of misfires is one or more faulty fuel injectors. An injector can fail mechanically or electrically, causing fuel not to be metered into the corresponding cylinder. This results in no combustion catalyst and robs the cylinder of power.
#5 – Loss of Compression
Rarely, misfires can occur due to a loss of compression in one or more cylinders. This is more common on high mileage engines and older models. Severe damage to the cylinder head gasket can also lead to a sudden loss of compression.
#6 – Misfires due to Emissions Controls
Faulty or inadequate exhaust emission control equipment can also be the cause of consistent misfires in one or more cylinders of your engine. This most commonly occurs when the EGR valve is stuck in the open position.
Is it safe to continue driving?
If your car’s check engine light is currently flashing and accompanied by a noticeable shudder, it’s best not to drive any further than necessary to reach a safe destination. Unlike a “Service Engine Soon” light, this can have serious consequences.
An example of this would be damage to your vehicle’s catalytic converter, which occurs whenever too much fuel enters the engine’s exhaust due to a general lack of spark. This will prevent further issues from occurring, which often cost quite a bit to repair.
If you’re not confident enough to diagnose and fix the problem yourself, make an appointment with a good independent mechanic or dealership service center as soon as possible.