It's an occurrence that can strike fear in even the most experienced drivers; it can conjure images of expensive mechanic bills and vehicles stranded in the middle of the open desert; it's the dreaded check engine illuminating behind your steering wheel.
While it might trigger immediate panic, the truth is that the check engine light can often pop up for minor problems that can be a quick and easy fix. It can also signify a larger issue, however, so you should look into it as quickly as possible.
Before you panic and begin shopping for a new vehicle, here's a quick overview of the seven most common reasons your check engine light has been activated:
What it means: Over time, your vehicle's oxygen sensor can become dirty and covered in oil. A dirty oxygen sensor won't prevent your vehicle from running, but it can lower your gas mileage and cause you to fail an emissions test. It can also lead to a broken catalytic converter, which will cost way more than an O2 sensor replacement.
What you should do: You can either ask a mechanic to replace your O2 sensor, or you can follow the instructions in your owner's manual and do it yourself. Expect it to cost anywhere between $50 and $300.
What it means: If your check engine light comes on shortly after you've filled up on gas, your gas cap could be loose or broken. Because the gas cap helps maintain the fuel system's correct pressure, a dysfunctional one can throw off everything. You could end up losing fuel and increasing your emissions output.
What you should do: Ensure the gas cap is on and tightened. If that doesn't work, you can purchase a new gas cap for under $20 at most auto parts stores.
What it means: The catalytic converter is a crucial part of ensuring your vehicle isn't emitting harmful toxins by converting carbon monoxide into carbon dioxide. Over time, it can become dirty and clogged and often breaks if other parts of the engine aren't well maintained.
What you should do: If you notice unusual noise, an inability to increase speed, cloudy exhaust smoke or a decrease in gas mileage, you should visit a mechanic to replace the catalytic converter. Expect to pay between $1,000 and $2,000.
Spark plugs and ignition coils
What it means: Spark plugs and ignition coils are what help a vehicle start and accelerate. If the vehicle is properly maintained, they should only need to be replaced every 100,000 miles or so. But be warned, waiting too long could result in damage to the catalytic converters and other expensive engine parts.
What you should do: Have your mechanic check these regularly. Replacement for a single spark plug can cost around $20 and a new ignition coil can cost about $50.
Mass airflow sensor (MAF)
What it means: Your mass airflow sensor measure the amount of air enters the engine and adjusts as necessary when you change altitude. A broken one will increase emissions, cause the car to stall, and decrease gas mileage.
What you should do: Keep your MAF safe and long-lasting by regularly replacing your air filter. If it's time to replace the MAF, use your owner's manual or ask a mechanic to install a new one, which should cost around $200.
One of the best ways to keep an eye on your car and it's internal components is to use a car health monitor and tire pressure monitor, which can keep tabs on your engine health and tires with real-time alerts and decode engine error codes, which can cause expensive diagnostic trip to the mechanic.