check engine light.

Check engine light started flashing

In Automotive Diagnostics by HomeTowne Auto Repair & Tire

Written by Erin Flynn

My work week had an unexpected (and slightly stressful) start.

I had filled up the gas tank for my Volkswagen Beetle on my way to work. But when I was leaving the gas station parking lot, my vehicle began to shudder. 

It stopped and then started shuddering again a little while later. As I was traveling down the road and preparing to merge onto I-95, the check engine light began to flash. “Oh no,” I thought to myself. A few minutes passed, and the light became solid.

I decided to have my car checked out and I cautiously made my way to HomeTowne Auto Repair & Tire. With a lot of luck, I arrived safely and explained my experience to the employees.

Valve cover on Volkswagen.

Determining the problem

When checking my car, the Woodbridge mechanics found out that it needed a new ignition coil. 

They used a scan tool and noticed that there was a misfire, which means that the air in the fuel isn’t igniting the way it should. This problem may be the result of a bad spark plug or ignition coil, or too much or too little air or fuel.

Some symptoms of a misfire include the check engine light coming on, and a vehicle stalling, running rough or shuddering.

After the misfire occurred on cylinder 3, the technician swapped out one of the ignition coils with another one and saw the misfire followed to cylinder 2. If there had been an issue with the spark plug, the second misfire would have happened on cylinder 3.

Ignition coils, which can be found in most makes and models, command a spark plug to spark. Poor connection and oil intrusion can cause them to fail. They can also go bad over time. 

Ignition coil.
Ignition coil

Why did my check engine light turn on?

An ignition coil or spark plug going bad are a couple of culprits behind a check engine light turning on. However, there are many causes, such as a loose gas cap, low oil, a malfunctioning catalytic converter, and problems with the coolant system.

Meanwhile, a flashing check engine light may be a sign that there is an engine problem.

More reasons why the light turns are explained in an article posted on

If you noticed that the check engine light came on and is remaining solid, there’s no need to panic. But the sooner you have your vehicle checked out, the better. Choosing to have it looked at early on can help automotive professionals pinpoint the issue more easily and quickly. 

However, if your vehicle starts shuddering or your check engine light comes on, you should have a mechanic or auto repair shop look at it immediately. We also recommend that you avoid driving the car. Waiting to address a blinking check engine light could lead to bigger, more expensive issues, like catalytic converter damage.

It’s also a good idea to reach out to an expert if any other lights appear, or if you notice strange behaviors or sounds. To learn about dashboard lights and what they mean, check out this article we posted.

HomeTowne Auto Repair & Tire is an authorized Michelin and BFGoodrich tire dealer located in Woodbridge, Virginia. Automotive repair services are performed on all makes and models, including oil changes, brakes, alignments, inspections, and computer engine diagnostics.