How To Clear OBD2 Codes Without A Scanner

If your vehicle checks engine light is on, there must be some problem in your vehicle. But, if you want to clear the obd2 codes without a scanner, then you can do this in just a few minutes.

In this guide, we will learn how to clear obd2 codes without a scan tool? If your query is similar, read this guide and learn the steps.

Why my engine check light is glowing?

Check engine light on

The ECU (electronic control unit) has all the information about your vehicle. There are many sensors connected to the ECU that give all the vehicle information.

Wherever any sensor detects an error, it gives information to the ECU. The ECU stores the error code in digital format and turns on the malfunctioning light (check engine light).

OBD2 scanners are used to detect those problems and the mechanic fixes them. Once it’s fixed, the ECU deletes that error code from memory with the help of obd2 scanners.

How To Clear OBD2 Codes Without Scanner?

If you don’t have an obd2 scanner and you want to delete the error code from the ECU memory, then there are some secret tricks to do this.

Here’s a step-by-step process for how to clear obd2 codes without a scanner-

Step #1: Park your vehicle

In order to perform the tricks, you need to park your vehicle somewhere in a peaceful environment. Don’t forget to engage the parking brakes.

Step #2: Open front hood

Clear OBD2 Codes without Scanner

Open the front hood of your vehicle where the battery is located.

Step #3: Remove negative (-) terminal

Car Battery Terminals

Use a spanner/wrench to disconnect your battery’s negative (-) terminal. Make sure it doesn’t touch your vehicle’s body.

Step #4: Disconnect positive (+) terminal

Car Battery

Now, remove the positive (+) terminal of your vehicle battery. You should ensure that both terminals should not touch each other.

Step #5: Turn ON-OFF-ON

Car Ignition

Head over inside the vehicle and turn ONOFFON 3 to 5 times. It’ll discharge all the capacitors.

Step #6: Press the horn button

Car Horn

Press and hold the horn button for 30-40 seconds. It drains all the power stored in the ECU capacitors.

Step #7: Connect the battery terminals

By pressing the horn, you’ve drained all the power from ECU. It’s recommended to wait for 5 minutes before connecting the terminals.

Connect positive (+) first, then negative (-) terminal. If you don’t follow this, you’ll notice a spark while connecting the positive terminal later.

Step #8: Turn ON the ignition

Turn ON the ignition and check for malfunctioning light on the console. You’ll see that: the check engine light is OFF.

Note– You might face a little issue in ignition because you already drained all the power. So, after starting the engine, run it for 2-3 minutes to warm up the components.


Resetting the malfunctioning light is quite easy. It would help if you followed the steps mentioned above to clear obd2 codes without an obd2 scan tool. If the check engine light turns on, it means you haven’t drained the ECU capacitors completely. Repeat the same steps to drain the power completely.

Hi, I'm Richard, an ASE-certified mechanic in Florida, USA. I love to optimize car ECU for better fuel economy and troubleshoot engine code errors and fix them.

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