Why Is My Car's Check Engine Light Coming On and Off Randomly?

Why Is My Car's Check Engine Light Coming On and Off Randomly? | Snider Auto Care

You're driving from work, and suddenly, the check engine light flickers on your dashboard, only to disappear as quickly as it appeared. Maybe it stays lit for a few minutes or miles. Confusing, right? Let's dive into why this mysterious little light might be playing hide and seek in your car.

What Does the Check Engine Light Mean

The check engine light, a critical component of your vehicle's onboard diagnostics system (OBD), is designed to alert you to potential issues with your engine or related systems. When this light illuminates, it's an indication that your vehicle's computer has identified an anomaly in the engine or exhaust system operations. The reason behind this problematic light could be more than one thing - most commonly it's a few at once.

Unlike other warning lights on your dashboard that indicate clear and specific issues (like the battery or oil lights), the check engine light serves as a general alarm for multiple possible problems. This ambiguity often leads to a bit of frustration and confusion among drivers.

Why Is My Car's Check Engine Light Coming On and Off Randomly?

Now, why does this light come on and off randomly? The intermittent flickering or flashing of the check engine light can be perplexing. This irregular behavior often indicates a problem that comes and goes, which can be more challenging to diagnose than a persistent issue.

For instance, a loose gas cap might cause the light to turn on, but once the cap is tightened during a stop, the light could turn off again. Similarly, variable engine conditions, like changes in humidity or temperature, can cause intermittent sensor readings that trigger the light. Sometimes, it's only visible under certain RPMs or at a lower engine temperature.

No matter the reason, the best thing you can do is visit a repair shop!

3 Common Reasons For A Lit Check Engine Light

Loose Gas Cap
Yes, something as simple as a gas cap not being tightened properly can trigger the light. It's the first thing you should check.

Faulty Oxygen Sensor
This sensor measures how much-unburned oxygen is in the vehicle's exhaust system. If it's faulty, it can cause inaccurate readings, leading to the light turning on.

Aging Spark Plugs
Spark plugs ignite the fuel in the engine. Over time, they wear out, and if they aren't replaced, can cause the check engine light to come on.

3 Uncommon Reasons For A Lit Check Engine Light

Catalytic Converter Failure
This component reduces exhaust gasses. If it fails, it not only triggers the light but also reduces fuel efficiency and engine performance.

Mass Airflow Sensor Issue
This sensor measures the amount of air entering the engine to determine how much fuel is needed. Problems here can cause the engine to misfire.

Exhaust Gas Recirculation Valve (EGR) Problems
This valve reduces nitrogen oxide emissions. If it's faulty, it can lead to performance issues, triggering the check engine light.


Does your dashboard look like a light show? Snider Auto Care is here to help. It's as simple as giving us a call, booking an appointment, and leaving the rest to us.

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