Why Is My Check Engine Light Flashing? Understanding Your Car’s Signals

Discover why your check engine light is flashing and what it means for your car. Learn about common causes and why immediate attention is crucial.

Everyone dreads the moment their check engine illuminates on the dashboard. But if you see your check engine light blinking on and off instead of glowing steadily, it can indicate a severe problem. So, if your check engine light starts to flash, it’s essential to know what could be happening under the hood. 

Read on to discover potential answers to the burning question, “Why is my check engine light flashing?” and what it could mean for your vehicle.

What Does a Flashing Check Engine Light Mean? 

The check engine light is how your vehicle communicates that something isn’t working as it should. To identify potential issues, your engine control unit (ECU)—essentially the brain of your vehicle—constantly monitors readings from numerous sensors throughout your car, such as mass airflow sensors, temperature sensors, crankshaft position sensors, and more. 

When the ECU receives a reading outside of acceptable parameters, it triggers the check engine light to glow steadily or flash, depending on the urgency of the potential problem. Solid check engine lights can signal many vehicle issues — many of which can be minor, like a loose gas cap. On the other hand, a flashing check engine light is your car’s way of letting you know that its ECU has detected a serious problem, like severe misfiring, that needs immediate attention. 

Common Causes of a Flashing Check Engine Light

• Engine Misfire: When your engine misfires, one or more cylinders fail to ignite correctly, which can place severe stress on mechanical components, allow unburned fuel to enter the exhaust system, and potentially damage your catalytic converter. Often accompanied by a reduction in power and loud popping or knocking noises, misfiring can be caused by worn-out spark plugs, ignition coils, or fuel system issues. 
• Bad Oxygen Sensor: Your vehicle’s oxygen sensor reports the air-fuel ratio in your engine to the ECU. If this sensor fails, your ECU can no longer accurately adjust the air-fuel ratio for your engine, which puts it at risk of misfiring and other serious issues that could cause your check engine light to flash. 
• Failing Catalytic Converter: Your catalytic converter is a crucial component of your exhaust system. It uses precious metals like platinum to convert harmful components in exhaust gasses like carbon monoxide into safer ones like carbon dioxide or water. When the delicate honeycomb of your catalytic converter gets damaged or clogged, it can prevent exhaust gasses from exiting your engine effectively, which may lead to overheating of the converter and even permanent engine damage.
• Faulty Exhaust Gas Recirculation (EGR) Valve: Your vehicle’s EGR valve helps reduce emissions by recirculating a portion of exhaust gasses back into the engine cylinders to lower combustion temperatures and increase efficiency. When EGR valves get clogged or stuck open, it can disrupt your engine’s air-fuel ratio and cause engine misfires. 
• Failing Vehicle Speed Sensors: Your vehicle or wheel speed sensors provide crucial data about how fast your vehicle is moving to your engine’s ECU. If one of these sensors fails, it can disrupt functions like fuel injection timing or transmission shifting, leading to engine misfires or other serious problems that cause your check engine light to blink. 

Is It Safe to Drive with a Flashing Check Engine Light?

We don’t recommend driving with a flashing check engine light — especially for an extended period — since it usually indicates a serious problem with your vehicle. Continuing to drive could damage your engine or other critical components further, increasing repair costs and potentially leaving you stranded. 

Instead, you should pay attention to any unusual smells, vibrations, or noises produced by your vehicle. Clues like these can help a mechanic diagnose the problem faster. Then, bring your car to a reputable auto repair shop or dealership for diagnostics and repair as soon as possible. 

Is Your Check Engine Light Flashing? Ed Hicks Nissan Can Help

Don’t ignore that flashing check engine light—it could be your vehicle’s way of saying, “Bring me in!” At Ed Hicks Nissan, our expert technicians can quickly diagnose and fix any issues to help keep you on the road. Book a diagnostic appointment with us, and drive confidently, knowing your engine is in top shape. Don’t let a mystery light put a damper on your plans—get it checked today!