A flashing check engine light is your car’s way of telling you: “Pay attention to me now.”
Unlike a check engine light that comes on and stays on, a flashing light can indicate a more serious problem, often an engine misfire that could damage your vehicle if you continue driving.
The good news is you don’t need to understand everything happening under the hood. You just need to know why the light may be flashing, what to do next and how to get reliable information.
Why Is My Check Engine Light Flashing?
One of the most common reasons for a flashing check engine light is an engine misfire. A misfire happens when one or more of the engine’s cylinders isn’t operating properly.
When this happens, unburned fuel can enter the exhaust system and potentially damage the catalytic converter, an important and expensive emissions-control component. That’s why your vehicle uses a flashing check engine light to get your attention.
Can I Keep Driving With a Flashing Check Engine Light?
It’s best to minimize driving and have the vehicle checked as soon as possible.
If the vehicle is also shaking, losing power, making unusual noises or showing other warning signs, find a safe place to stop and seek professional or roadside assistance.
A flashing check engine light isn’t something to ignore just because the vehicle still seems to be running. Continuing to drive with a serious misfire could potentially turn one repair into a more expensive problem.
Is your check engine light on but not flashing? Read our related article, What Does Your Car’s Check Engine Light Really Check?
What Can Cause an Engine Misfire?
There isn’t one single cause, which is why proper diagnosis is important. A misfire can be related to problems involving:
- Spark plugs or ignition coils
- Fuel injectors or the fuel-delivery system
- The engine’s air/fuel mixture
- Internal engine components
What Are Some Common Misfire Codes?
If your vehicle is scanned, the diagnostic report may show a code beginning with P030. Some common misfire-related codes include:
- P0300: Random or multiple-cylinder misfire detected
- P0301: Cylinder 1 misfire detected
- P0302: Cylinder 2 misfire detected
- P0303: Cylinder 3 misfire detected
- P0304: Cylinder 4 misfire detected
On engines with more cylinders, the numbering can continue with additional cylinder-specific codes.
Keep in mind: A trouble code is a starting point for diagnosis, not necessarily an instruction to replace a particular part. Several different problems can contribute to a misfire, so identifying the underlying cause is important before making a repair.
How Do I Find Out What’s Causing the Problem?
When your vehicle detects a problem, its on-board computer stores diagnostic information that can be accessed using an OBD-II scan tool. You don’t necessarily need to own one. Many auto parts retailers offer free warning-light scans that can retrieve the diagnostic trouble code stored in your vehicle.
The code provides an important clue about what’s happening. From there, a qualified repair professional can use the code, your vehicle’s symptoms and additional diagnostic information to determine the underlying cause and recommend the appropriate repair.
How CarMD Connect Can Help
CarMD Connect can help take some of the mystery out of the process.
If you receive a compatible diagnostic report, you can scan its QR code in the free CarMD Connect app to get additional information about the problem, including problem severity, repair guidance and cost information. You can also use AskCarMD, the app’s AI Auto Expert, to ask questions about dashboard warning lights and vehicle problems 24/7.
The goal isn’t to turn you into a technician. It’s to help you better understand what’s happening with your vehicle, know what questions to ask and have a more informed conversation with a repair professional.
The Takeaway: Don’t Ignore a Flashing Check Engine Light
Your check engine light is designed to give you an early warning when your vehicle detects a problem. When that light flashes, take the warning seriously.
Minimize driving, get the problem checked promptly and remember that a diagnostic trouble code is the beginning of the diagnostic process, not necessarily the final answer. Understanding the problem before moving forward with a repair can help you make a more informed car care decision.