What is the check engine light

Your vehicle check engine light is an integral part of your vehicle maintenance. When you see a service light on in your car, truck or van, you should never ignore it. Instead take initiative to see what the service light is for, and how to remedy the issue.

Today I’ll be going over the check engine light, otherwise known as the Malfunction Indicator Lamp. The check engine light in your vehicle is for your On Board Diagnostic system, otherwise known as your OBD computer.

What does my check engine light mean?

This check engine light could mean that there’s a problem with your vehicle’s emission system. It could also be warning you of an issue with your powertrain or your engine as well. Most of the time however, your check engine light will be triggered from an issue somewhere in your emission system.

Of course, your emissions system includes several sensors known as the oxygen sensors or 02 sensors. These sensors are part of your emissions system and are used to read your engine’s exhaust. By reading the amount of air-fuel ratio present in your exhaust gases, your vehicle oxygen sensor can tell if your catalytic converter is working and if your engine is running right.

Your catalytic converter is also known as your three-way converter, and it’s used to reduce harmful emissions. When your engine computer detects an issue with any of your internal systems, it will trigger the light to turn on.

This problem can cause increased fuel consumption in your vehicle, or lead to premature failure of your engine. The absolute least that a check engine light means for you is that your car is no longer legal and won’t be able to pass any state and local vehicle emissions tests.

What can I do when my check engine light is on?

The first thing to do when your CEL trouble light is turned on in your dashboard or your instrument cluster is to take action. Don’t forget the longer you allow this problem to linger or leave it unaddressed, the more the repair may end up costing you.

Before you rush out to get a check engine light reader, or OBDII scan tool, you will want to do some easy check engine light troubleshooting on your own.

Here are a few simple things to check before you get to some serious troubleshooting.

Gas Cap – One of the most commonly misdiagnosed trouble codes is caused by a loose gas cap. When your gas cap is insecurely tightened down, it can lead to problems with your fuel re-circulation system.

So if you’ve recently filled up with gas and found that your check engine light is on, check the gas cap before you do anything else.

Loose connectors – Open your hood and give your engine a once over to check for loose connections. Pay particular attention to the oxygen sensors or connectors on your engine.

Make sure none of them are loose or damaged, which could cause your check light to turn on.

What triggers my check engine light?

If you’ve done the simple steps and your check engine light is still on, you’ll need a professional scan tool. These tools help you read the alphanumeric trouble codes stored in your engine computer. In case you don’t know what kind of OBD your vehicle is, make sure to check your vehicle year model. Models built after the 1996 model year are all OBD2 or OBDII compliant.

The OBDII system in your vehicle is a set of standardized protocols, made to help identify the problem with the car. Fault codes and trouble codes can be retrieved using a professional scan tool.

In the hands of a trained technician, this tool can help you check the source of your check engine light. These professional tools are typically very expensive, but there are now OBDII scan tools that you can use with your cell phone that will do just as good of a job.

In case you need help with using an OBDII scan tool, check out our guide here. Can I replace the part that’s causing the check engine light myself? For most emissions-related problems, yes you can replace the part yourself. Whether that’s an engine sensor like your throttle, MAP or MAF sensor, these parts are simple and easy to replace.

What could be some other problems?

Some other sensors that are part of your emissions system but may be a little harder are oxygen sensors. These O2 sensors are made to read the exhaust to determine if your engine is running right, and your catalytic converter is running well.

If you have found that your vehicle check engine light has been triggered by a faulty oxygen sensor, you’ll need a proper replacement. This means you’ll need a new sensor that is designed to work just like your original unit, and have the proper wiring and wiring connector to restore your engine operation.

Typically the hardest part of replacing your oxygen sensor is removing it. Over time the multiple heat cycles may have caused your primary or downstream O2 sensor to seize.

Once you’ve got the bad oxygen sensor removed, it’s a good idea to use an anti-seize compound on the threads to make removal easier next time. Once you’ve got the new oxygen sensor in place and secured, you’ll need to reconnect the harness to your engine to restore engine operation.

Make sure to clear the check engine code properly. and after that, a proper road test is in order. Have any questions about troubleshooting your engine light or replacing any of your engine sensors? Leave us a comment below and let us know!