How To Clear OBD2 Codes Without A Scanner: Is It Possible?

How To Clear OBD2 Codes Without A Scanner: Is It Possible?

When we talk about clearing OBD2 codes we’re really talking about how to remove the “check engine” light that has come on.

The good news is that this can be removed quite easily, even if you don’t own an OBD2 scanner. There’s no doubt that this light can be annoying if it never wants to go away!

But, should you remove the “check engine” light? This light shows you that there’s a malfunction in your car, such as a problem with its anti-lock brakes, airbags, or transmission.

It’s therefore important and calling for your attention! With that in mind, let’s explore times when you would need to remove the check engine light.

We’ll also look at how to go about this even if you don’t own an OBD2 scanner

Before You Clear The “Check Engine” Light Error Code

Before You Clear The “Check Engine” Light Error Code

It’s important to find out what is causing the “check engine” light trouble code to come on in your car instead of just trying to remove it.

This light can give you valuable information about something that’s wrong or malfunctioning, so you should never take it lightly!

You should always ensure that you’ve fixed the problem causing the light to come on, otherwise clearing the light is not going to do you any favors.

It will just come back on because the problem will still be present.  

How To Clear Codes Without An OBD2 Scanner

If you’re sure you want to proceed with erasing the codes and you want to know how to do this, you might think you need to use an OBD2 scanner.

These types of tools can erase “check engine” light codes pretty easily. However, you don’t have to have an OBD2 scanner. Here’s how to remove the code without a scanner.

  1. Start by parking your car in a level and safe area.
  2. Engage the parking brake and open the hood.
  3. Remove the negative cable from the car battery (it’s the black cable, in case you didn’t know) and loosen the battery terminal clamps with a wrench.
  4. Once you’ve done that, you should also remove the positive cable from the battery (this cable is red in color). Don’t let the cables touch each other! 
  5. Cycle the ignition switch to the “on” and “off” position three times.
  6. On the steering wheel, press the horn button for 30 seconds to drain out the power in the ECU. This works well because the horn is linked to a hot circuit.
  7. Reconnect the battery to its cable, starting with the red one and then the black one.
  8. Turn on the ignition and check for any warning lights to show up on the console.
  9. Start the engine and let the car warm up. You’ll likely see that the “check engine” light does not come back on. 

What You Can Expect After Doing The Above Steps

What You Can Expect After Doing The Above Steps

You might find that your car is behaving a tad strangely, such as by rough idling, but this shouldn’t concern you because the car’s onboard computer is simply adjusting itself.

The settings will be recovered and the car will be back to normal in no time. To help the process along, it’s good to drive your car normally for a while after you’ve reconnected the battery. 

Is It Illegal To Remove The “Check Engine” Light?

Is It Illegal To Remove The “Check Engine” Light?

Now, you might be wondering if it’s even legal to remove your “check engine” light yourself. If you’re doing this as an attempt to try to pass your car emissions test, which is mandatory in most U.S. states, then this is a bad idea.

It won’t even work, because your car will need to be driven for many days in order for the EVAP and catalyst monitors to have enough time to get up and running again.

If your “check engine” light reappears, this means that there’s a fault with the car that needs to be dealt with. If you don’t sort out that problem, then your car will fail the test.

Similarly, it’s illegal to remove this warning light from your car if you are trying to sell your vehicle and you don’t want the new owner to be aware of problems with the car.

You could get into serious trouble because doing this is known as fraudulent concealment. 

What To Do If Your “Check Engine” Light Comes Back On? 

What To Do If Your “Check Engine” Light Comes Back On?

If you’ve tried the previous steps we’ve outlined to help you remove the “check engine” light from your car, only to find that it returns, the message is clear: you need to take your car to a mechanic so that the reason for the light coming on can be addressed.

Otherwise, it just won’t go away! 

What Does The “Check Engine” Light Mean? 

You know that a check engine light that stays on means that something’s wrong, but let’s take a closer look at what could be the problem with your car. 

Some common problems that could cause the “check engine” light to come on include issues with the catalytic converter, ignition coil, spark plugs and wires, oxygen sensor, mass air flow sensor, and charging system.

Now, there are times when the “check engine” light is serious. How can you tell? Here’s what to look for:

  • If the check engine light is steady yellow or orange, then you don’t need to stop the car immediately or drive straight to your mechanic. There could be a minor problem with your car, but you don’t want to risk your car’s wellbeing by ignoring it. Either book an appointment with your mechanic so that your car can be seen to, or purchase an OBD2 scanner so that you can try to find out the source of the problem yourself.
  • If the light starts flashing, this requires you to stop the car immediately because it’s usually a sign that there’s a serious problem with your car and you shouldn’t be driving it otherwise you will do real damage to it.

Can You Use An OBD2 Scanner To Erase Codes?

Can You Use An OBD2 Scanner To Erase Codes?

This type of tool is highly useful because it will not only alert you to what is wrong with your car but it can also be used to clear the codes.

If you don’t have a scanner handy and you don’t want to purchase one, you can borrow one from a friend or your local auto shop.

Here’s how to use a scanner to remove codes:

  • Start by inserting the scanner into your car’s OBD2 port.
  • Turn the key in the ignition to the “on” position and then press “read” or “scan” on the scanning device, depending on the model you’re using. 
  • When the lights on the dashboard come on in your car, turn off the car’s accessories (like its radio) and press “read” or “scan” on the scanner so that the device can read the “check engine light” code.
  • Once you’ve done that, you’ll be able to press “clear” or “erase” to remove the “check engine” light. You should now wait until the “no codes” message comes on the scanning device. 
  • Turn off the car and remove the scanner from the OBD2 port.

Of course, erasing the code will only be a temporary solution for the “check engine” light.

You’ll see that it will return after a short while if you have not repaired whatever needs to be fixed in your car, so don’t expect it to go away for good! 

Related Questions 

How long does it take for the “check engine” light to reset?


Once you have repaired the car’s problem, it will take about 10 to 30 cycles before the light will disappear.

One cycle can be defined as going from a cold start to when the car’s engine is at working temperature.

Will a mechanic reset your “check engine” light?

Any reputable and lawful mechanic or auto shop will not reset this light without first repairing whatever is wrong with your car that caused the light to come on in the first place. 


If you need to clear your OBD2 codes, the good news is that you can do so without the help of your mechanic. You don’t even need an OBD2 scanner, as we’ve seen in this article.

Clearing an OBD2 code is pretty simple once you know how to go about it. But, as we’ve outlined in this article, there are some important things to bear in mind.

Make sure that clearing your OBD2 codes is legal and done correctly without putting the health of your car at risk. 


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