Is your ‘check engine’ light on? Here are 10 reasons why

The orange, engine-shaped icon that sometimes appears in your car’s instrument cluster isn’t just a nuisance; it’s a sign that something is wrong under the hood. Ignoring it could leave you stranded at the worst possible moment, cost you thousands, or both.

The check engine light warns of issues ranging from a gas cap that’s not properly tightened to a more serious failure like a bad catalytic converter. Here are the ten most common problems that can trigger a check engine light.

My check engine light is on — now what?

Modern cars are brimming with high-tech bells and whistles, but you still need a separate, aftermarket device to decipher why the check engine light is on. Most motorists simply take their car to the dealership. That’s the easy way out, but it’s also the most expensive route to take.

If you want to skip a trip to the repair shop, spend a few dollars on a Bluetooth-compatible OBD II scanner (or a more advanced adapter)  and download a compatible app like Torque from either the Google Play Store or Apple’s App Store. You can get the tool and the app for less than $15.

Ready? Start by finding your car’s OBD II port. It’s usually in the driver’s footwell, not far from the hood release, but sometimes it’s hidden behind the center console or in a compartment built into the floor. Plug in the scanner, launch the app on your phone, and the error codes stored in the car’s ECU will appear on the screen. Sometimes the codes are clearly explained; other times you’ll need to do a bit of searching to figure out what P1301 means.

There are professional-grade code scanners that are more precise but also much more expensive. Alternatively, some auto parts stores will run a diagnostic test for free. However, getting a Bluetooth scanner and an app will save you time and money while making you more car-savvy.

So the check engine light tells me when I should fix my car?

The check engine light provides an idea — sometimes precise, sometimes vague — of what’s wrong with a car. However, it doesn’t replace a skilled mechanic.

In other words, don’t wait until the check engine light comes on repair your car. The ECU is not going to warn you that the water pump is about to fail, that one of the ball joints is worn, or that the A/C is going to stop blowing cold air in mid-August. If your car drives, sounds, or smells funny, either fix it or take it to someone who can.