Check Engine Light: What You Need to Know

The check engine light warns drivers that something is wrong and occurs when the computer issues an error message.

What does it mean when my check engine light comes on?
A glowing check engine light means that the onboard diagnostic system has detected a problem affecting the emission controls. There are dozens of possibilities as to why it has illuminated. It could be something as simple as a loose gas cap, bad airflow, a bad oxygen sensor or a faulty catalytic converter. When this warning light comes on, it generates a trouble code that can be read by connecting a diagnostic scanner to the vehicle's onboard diagnostic system; that will steer your mechanic to specific areas and help find the cause. A flashing check engine light means the problem is serious enough that it warrants immediate attention to prevent expensive repairs. Stop as soon as it is safe to do so.

How soon do I have to get my check engine light checked once it illuminates?
Though a check engine light doesn't always signal that something needs immediate attention, it shouldn't be ignored. While it might be minor, it could be something bad, something that will grow worse quickly if left unchecked. For example, a faulty oxygen sensor can reduce fuel economy, raise emissions and cause the catalytic converter to overheat. Replacing a catalytic converter will be much more expensive than an oxygen sensor. If the check engine light is flashing that means the situation is dire and needs to be addressed pronto.

Why is it important to diagnose an illuminated check engine light?
The only way to find out what caused the check engine light to illuminate is to have a mechanic connect a diagnostic scanner to the onboard diagnostics system to extract trouble codes that will help locate the source. The sooner that's done the better.

How much should I pay?
The cost of repairs can depend on where you are as much as it does on what you need fixed. To get an estimate for your repair, go to our estimator, plug in your car's year, make and model information, add your ZIP code, and choose the repair you need. We'll give you a range for what your repairs should cost in your area.