When there is a problem with your vehicle’s emission control system or another computer-controlled system, your check engine light normally illuminates. But if the issue has been resolved but the problem is still present, you can be confused and not sure of what is happening.
Despite the possibility that your car still has problems, the likelihood that you simply need to reset the light is very high. So, the question is, how can you reset the check engine light?
Resetting a car’s check engine light can be done with and without a scanner. Well, to reset a check engine light without a scanner, disconnect the negative battery cable and wait for a few moments.
Your car’s diagnostic system will be reset as a result, and if the underlying problem has been fixed, the light should go off right away.
Some common causes of why the check engine light comes on are a loose fuel cap, transmission, engine oil, oxygen sensor, emission problems, spark plug, ignition coils, wiring issues, and fuel system.
Now, let’s go deep to explain how to reset a car’s check engine light with and without a scanner and the common causes why the check engine light comes on!
Related: What Does Check Engine Light Mean? Causes And How To Fix
How to reset the check engine light With a Scanner
Here’s how to reset the check engine light with a scanner:
- To reset the check engine light using an OBD scanner, plug the reader into your car’s OBD port. This port is typically found directly above the footwell on the bottom of the dash. To reach this connector, you may need to open the fuse box door on certain vehicles.
- Once the reader is connected, switch it on by pressing the “enter” button.
- Your engine will be scanned by the gadget for any error codes. When it’s completed, the reader will show any errors that it finds. If you want to double-check the codes in the code reader’s handbook or online, make a note of the codes (if any).
- By pressing the “scroll” button, you will find the option to erase the code. To clear the fault code and reset the check engine light, select the option and press enter.
How to Reset a Check Engine Light Without a Scanner
Here’s how to reset the check engine light without a scanner:
Drive Your Car and Let the Light Go Off by Itself
Driving and patience are the first and easiest ways of resetting the check engine light. The majority of onboard computers will check the issue that triggered the check engine light several times.
Drive your car as usual. Three days later, if the check engine light is still on, your issue might not have been resolved, so proceed to the next method below.
Turn the Car on and Off Three Times
After being started and stopped three times in quick succession, some vehicles will automatically reset the trouble codes that resulted in the first issue.
To do this, turn on the ignition with your key in it for about a second, then turn it off for roughly the same amount of time. Then drive the car normally after doing these two more times. Check if the check engine light has been reset.
Disconnect and Reconnect the Battery
- Turn off the car’s engine.
- Open the hood and locate the car battery. Identify the negative terminal. It has a negative (-) sign or is black.
- Use a wrench to loosen the terminal, then hold the negative cable to the side for at least 30-60 seconds. Never allow cables to come into contact.
- To draw more power, have a friend hold the horn down.
- Put everything back in place and reconnect the negative cable.
- Check to see if the light goes out.
Related: Engine Sputtering: Most common causes and how to fix
Watch the video for more insight on how to reset the check engine light:
Reasons Why Your Check Engine Light Comes On
The following are the most common causes or reasons why your car’s check engine light comes on:
Loose Fuel Cap
This one is actually quite typical. Sometimes you don’t tighten the gas cap all the way (listen for the click), or perhaps you never replaced it in the first place. In any case, it’s a simple issue to identify and resolve.
Transmission
Transmission damage can also cause the check engine light to turn on and alert you to an issue, even if your transmission may have its own unique warning lights.
You might simply need a transmission service to replenish the fluid, or there might be more serious internal damage that needs to be fixed.
Engine Oil
You might not have enough oil, or the oil itself might be tainted and old. This will result in performance loss and engine issues that can set off the check engine light. It’s possible that you simply need to get your oil changed or that there is a leak in the fluid system.
Just a handful of the most typical reasons why the check engine light could come on are listed above.
Get your car checked out by a qualified mechanic if your check engine light is on, particularly if it is red or flashing, which denotes a serious issue that has to be fixed right away.
In order to identify the precise cause of the warning light, they might perform diagnostic tests and parts inspections.
Oxygen Sensor
Oxygen sensors are part of your emissions system and are used to identify problems with the exhaust. The check engine light would most likely come on if there are pollution issues.
The sensor itself may occasionally malfunction or produce inaccurate results, necessitating replacement.
Other Emissions Problems
The most frequent cause of check engine light illumination is the emissions/exhaust system. There can be a catalytic converter issue or an exhaust leak.
Another sensor that is readily tripped or susceptible to failure is the mass airflow sensor (MAF). If your check engine light is on, it is typically a good idea to get your exhaust system serviced.
Cooling System
Again, a car that is overheating will have its own temperature gauges and warning lights. The check engine light, however, could also come on if the cooling system isn’t working properly.
Spark Plugs or Ignition Coils
When one of your spark plugs or ignition coils is faulty, the check engine light will also often turn on. It’s possible that something isn’t firing properly, which could result in decreased engine performance, and the check engine light is alerting you to the issue.
Wiring Issues
A lot of wiring, from the battery to the spark plug wires and the ignition system in between, is necessary for your car to start and keep running smoothly. The check engine light may come on as a result of a loose connection or damaged wire.
Fuel System
The check engine light may turn on to alert you that something is wrong with the fuel system if your engine isn’t getting enough gasoline or if the fuel is contaminated because the filter needs to be replaced.
Related: What is Engine Mount? Its Causes & Replacement Cost
Is it safe to drive with the check engine light on?
You can continue driving for a short period of time, but make sure to schedule an engine inspection as soon as you can. Don’t freak out if the check engine light comes on while you’re driving! Keep an eye out to observe if the car is driving in any unusual ways.
Nevertheless, driving for a long period of time when the check engine light is on is typically not recommended. The check engine light is a warning sign that there may be a problem with your car’s engine or emissions system and that it may be serious and need quick attention.
The engine may suffer additional damage, there may be an increase in pollutants, and your car’s fuel efficiency may suffer if you ignore the check engine light and keep driving.
In some circumstances, it can even result in a complete breakdown of the car, leaving you possibly stranded on the road.
Check engine light FAQs
How long does it take for the check engine light to reset?
The check engine light will typically turn off automatically once the problem that brought it on has been resolved, but only after 10 to 20 “cycles”.
How do you turn off the check engine light on a Toyota?
Here’s how to turn off the check engine light:
- Put the car in park and wear your gloves and safety glasses.
- Find the negative terminal on the battery of your car.
- Loosen the nut on the negative battery terminal with a wrench, then remove the negative connector from the battery.
- Keep it disconnected for 30 to 60 seconds.
- Use your wrench to retighten the negative cable connection.
What to do after resetting the check engine light?
Typically, you should travel 50 to 100 miles after clearing the computer in your automobile. Hopefully, this will completely turn off the check engine light. If it doesn’t, a more serious issue may be making this light turn on.
Can you reset the check engine light without disconnecting the battery?
You can try starting the car for a brief period of time before turning it off to reset the check engine light. Most vehicles’ fault codes will be reset as a result of doing this, and the check engine light will go out.
Why is my engine light on but nothing seems wrong?
A loose gas cap is one of the less dangerous causes of a check engine light coming on, while a damaged catalytic converter is one of the more serious ones. Even worse, it can indicate an internal engine breakdown. Ignoring the issue may cause a potentially simple fix to become a pricey and time-consuming repair.
What is the most common reason for the check engine light to come on?
The most frequent cause of check engine light illumination is the emissions/exhaust system. There can be a catalytic converter issue or an exhaust leak. Another sensor that is readily tripped or susceptible to failure is the mass airflow sensor (MAF).
Can I drive with the check engine light on?
You should stop driving at this point and get your car checked out by a mechanic as soon as you can. When deciding whether to drive yourself or contact a tow truck to a local repair shop, use your best judgment.