In most cases, the “check engine” warning comes on for a reason. However, there are also some situations in which the check engine light won’t seem to turn off, even after you’ve fixed whichever issue caused it to come on in the first place.
A flashing check engine light should never be ignored, of course. But once you’ve done everything you can to ensure there’s no problem and the light’s just there, threatening to cause you to fail your safety or emissions test or just bugging you, you may choose to do a DIY reset.
In this post, we show you how to reset this warning light in 5 different ways, all of which are straightforward and not too time-consuming.
Contents (Jump to Topic)
Key Takeaways
Fix the Issue First – Before resetting the check engine light on your own, make sure that the issue that caused the light to come on in the first place has actually been fixed.
Don’t Despair – Often this problem is caused by minor issues like a loose gas cap, loose wire or plug, or a disconnected sensor.
Five Methods to Choose From – Resetting the light can be done using five methods, most of which don’t require specialized tools
How Do You Reset the Check Engine Light?
There are several ways you can go about doing this. Most are very easy to do, but some are not recommended as they can cause other secondary issues.
Here are several methods you can follow:
1. Fix the Issue Causing the Light to Illuminate
This should not come as a shock to anybody, but the best way to go about doing this is to fix the issue that is causing it to come on in the first place.
Every vehicle since 1996 is equipped with OBD-II, a universally mandated on-board diagnostics system that can be read by an OBD-II scanner.
This will help you or a mechanic diagnose and fix an issue that causes the check engine light to illuminate.
2. Just Wait
For some vehicles, the root of the problem can be addressed and fixed, and the light will go out. For others, the ECU will take some time to fully run through its cycle of checks, and could take days or weeks to clear fault codes after you’ve done the necessary repairs.
As long as you know that an issue has been fixed, there should not be any problems with simply waiting for the check engine light to turn off on its own.
Driving your vehicle around as you normally do will allow all ECU cycles to complete themselves.
3. Turn the Ignition On and Off Several Times
Turning your vehicle on and off several times in succession can also reset your check engine light.
This will only work on some vehicles, but it’s worth trying before moving on to any of the trickier methods.
4. Disconnect the Battery, and Drain the Remaining Power in the System
Disconnect the positive battery terminal, the negative terminal, or both battery terminals. You will need a wrench to unscrew the bolts holding the terminals onto the battery.
Make sure that the vehicle is off before you open the hood and disconnect any battery components.
It is also a good idea to turn on the vehicle’s headlights or hold the horn down for a minute after the battery is disconnected, to drain residual energy that might be in the capacitors.
Once everything has been disconnected and the remaining battery power has been drained, allow the vehicle to sit for up to 30 minutes. After that, reconnect the terminals, tighten them to the battery, and turn the ignition on.
Disconnecting the battery essentially erases the vehicle systems’ memory. Not only will doing this most likely reset the check engine light code, but the radio, anti-theft control system, and other components will likely be reset as well.
5. Clear the Fault Codes by Using an OBD II Scanner
The easiest, safest, and most common method to follow in modern vehicles is to clear the code or codes with an OBD-II scan tool.
To do this, plug in an OBD-II scan tool to the OBD II port of your vehicle. Your owner’s manual should pinpoint its location, but in most cases, it will be located next to the fuse box between the steering wheel and driver’s door.
Once the scan tool is plugged in, turn the vehicle on. Once the vehicle has been turned on, you’ll need to turn the scan tool on, let it boot up, and press “scan.”
The tool will then read the error codes, display them, and you will have the option to clear some (or all) of the codes that have been read by the scan tool.
Be sure to make note of each code present after the scan is complete.
After you’re done with all of that, press “clear” to erase the code or “enter” when asked if you are sure you want to clear the codes, and the check engine warning light should be successfully reset and no longer illuminated.
What Tools Do You Need to Reset the Warning Light?
Most methods of resetting check engine lights require a minimal number of tools. These are the ones you should still have some of these tools handy just in case your first attempts don’t work.
- Gloves
- Pliers or a Wrench
- OBD II Scanner (These connect to your vehicle’s OBD port via a cable, or they can be bought as Bluetooth devices with smartphone apps without cables, and will tell you what you check engine light means)
Why Would You Need to Reset the Check Engine Warning Light?
Most of the time, it isn’t recommended to do this, especially if you don’t know what is causing the issue.
However, there are a few situations in which you might want to perform this task. These situations include:
The Vehicle’s ECU Has Not Had Time to Reset Itself
A vehicle’s ECU often runs in a circuit, constantly monitoring sensors and systems to make the adjustments necessary to keep them running optimally.
When something abnormal is encountered, the ECU will try to correct the issue. If the issue isn’t able to be corrected, the check engine light will come on.
Because there are thousands of sensors and information points that your vehicle’s ECU handles, it might take a little while to figure out that there isn’t a problem after the issue has been fixed.
Every vehicle is slightly different, and older vehicles aren’t as sophisticated as the most modern ones. ECU cycles could take up to a few weeks to fully recognize when a problem is no longer there, depending on the vehicle.
The Vehicle Could Fail Safety or Emissions Testing
Each state has different requirements for vehicles to pass or fail a safety inspection. Some states also have an emissions test in addition to safety inspections.
For those states which have emissions tests, some will automatically fail your vehicle if the check engine light is on.
You Know There Isn’t a Problem
You have fixed your car, and you should expect your check engine light to go off.
If it doesn’t, you may want to consider resetting it so that any more problems that might occur aren’t overlooked, especially if your car takes a long time running through ECU cycles.
What Happens If the Warming Comes on Again After You Reset It?
If you have taken all the necessary steps there are to take, and it remains on or comes back on after turning off for a short while, you will most likely need to seek a mechanic’s advice.
Most of the time, this means that the vehicle is continuing to find a fault in one of its systems, and a potentially serious problem is recurring.
When to go to an Auto Repair Shop?
Mechanic shops, a repair shop, or many auto parts stores will often do a reset for you for free.
Even though OBD-II scanners are available for everyone, many people don’t have them, and others who can afford them aren’t confident in their abilities to use them properly.
Most likely, they will tell you what the check engine warning light is on and clear the code with the scan tools and code readers they have at their shop.
Wrapping It Up
As you’ve seen for yourself by now, resetting your check engine warning light is not a difficult process, but it should always be done with great discretion. After all, it’s there for a reason, and should not be neglected when it comes on. The best way to reset the check engine light is to fix the underlying problem that’s causing it to come on in the first place. Vehicles are so advanced these days that simply fixing the issue will cause the light to turn off on its own. With that being said, this doesn’t always happen, and it’s still good to know how to reset the check engine light if necessary.
