How do I manually clear my car code?

If your car's check engine light is illuminated, it's important to address the underlying issue as soon as possible. While the best approach is to have a professional mechanic diagnose and fix the problem, you can sometimes manually clear the check engine light yourself. This guide will walk you through the steps to manually clear your car's check engine light.

Steps to Manually Clear the Check Engine Light

1. Locate the OBD-II (On-Board Diagnostics) port. This is usually found under the dashboard on the driver's side of the vehicle.


2. Connect an OBD-II scanner or code reader. You can purchase a basic OBD-II scanner or use a smartphone app that connects to your car's diagnostic port.


3. Read the diagnostic trouble codes. The scanner or app will display the specific trouble codes that are causing the check engine light to illuminate. Make a note of these codes.


4. Clear the trouble codes. Most scanners or apps will have an option to clear the trouble codes, which will turn off the check engine light.


5. Disconnect the scanner or app. Once the codes are cleared, you can disconnect the device from the OBD-II port.

It's important to note that manually clearing the check engine light does not fix the underlying problem. The light will likely come back on if the issue is not addressed. If the light continues to illuminate, it's best to have a professional mechanic diagnose and repair the problem.

Reasons to Manually Clear the Check Engine Light

There are a few reasons why you might want to manually clear the check engine light:

• Temporary issue: If the check engine light is caused by a temporary issue, such as a loose gas cap or a minor sensor problem, clearing the codes may be all that's needed to turn the light off.


• Diagnostic testing: If you're taking your car in for repairs, clearing the codes can help the mechanic more accurately diagnose the problem.


• Emissions testing: In some areas, you may need to pass an emissions test to renew your vehicle registration. Clearing the codes can help you pass the test, but the underlying issue should still be addressed.

Remember, manually clearing the check engine light is a temporary solution and should not be used as a long-term fix for a persistent problem. If the light continues to illuminate, it's best to have a professional mechanic diagnose and repair the issue.

How to clear codes on a car without a scanner?

You can attempt to reset car codes without a scanner by disconnecting the negative battery terminal for at least 15 minutes or by cycling the ignition key several times. However, disconnecting the battery will erase your car's settings, including radio presets and clock, and the underlying issue must be fixed for the code to stay clear. These methods are considered temporary "first-aid" solutions. 
This video demonstrates how to reset your car's engine light without a scanner: 59sTampaTecYouTube · Apr 16, 2017
Method 1: Disconnect the negative battery terminal 

• Locate and disconnect: Open the hood and find the battery. Use a wrench to loosen the nut on the negative terminal (usually marked with a "-") and carefully remove the cable from the post. 
• Wait: Leave the battery disconnected for at least 15 minutes. This allows the vehicle's computer (ECU) to discharge any residual power. For older vehicles, you can briefly touch the disconnected negative cable to the positive terminal with a wrench to help drain the system faster. 
• Reconnect: Reconnect the negative terminal and tighten the nut securely. 
• Start the car: Turn the ignition to start the engine. The check engine light should be off, but you may need to reset your radio and clock. 

Method 2: Cycle the ignition 

• Turn on and off: With the key in the ignition, turn the key to the "on" position for one to two seconds, then turn it off for one to two seconds. Repeat this three or four times. 
• Check the light: Turn the ignition back on. This may force the computer to reset, but it is less reliable than disconnecting the battery. 

This video shows how to reset the check engine light by cycling the ignition: 59sMechanic BaseYouTube · May 24, 2023
Important considerations

• This is a temporary fix: If the underlying problem is not fixed, the light will come back on. If the light returns after these methods, the issue is still present. 
• Check your gas cap: A loose gas cap is a common cause of a check engine light, especially for EVAP system codes. Try tightening it, and then consider one of the methods above. 
• Potential for other settings to reset: Disconnecting the battery will likely reset other electronic settings like your radio presets and clock. 
• May not work on all cars: These methods are more effective on older vehicles and may not work on newer, more complex models. Disconnecting the battery on modern cars can sometimes cause issues with other systems. 
• Always diagnose the problem: It's best to get the specific code read with a scanner to properly diagnose and fix the problem. Many auto parts stores will scan your codes for free. 

Can I manually reset my check engine light?

Yes, you can reset the check engine light yourself, but it is important to first address the underlying problem. You can reset it by disconnecting the negative battery terminal for about a minute, pulling the correct fuse, or using an OBD-II scanner to clear the code. The light will likely come back on if the issue is not fixed, and resetting it may also clear your radio presets and other vehicle settings. 
Methods to reset the light
1. Disconnect the battery 
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This is a common method, but it can reset other electronic settings in your car. 

• Turn off the car and remove the key.
• Locate the negative battery terminal (usually black with a minus sign).
• Use a wrench to loosen the nut on the terminal and pull the cable off.
• Leave the cable disconnected for 30-60 seconds.
• Reconnect the cable and tighten the nut.
• Start the car to see if the light is off.

2. Use an OBD-II scanner 

• Purchase or borrow an OBD-II scanner. Many auto parts stores will scan it for free. 
• Locate the OBD-II port, usually under the dashboard on the driver's side. 
• Plug in the scanner and turn the ignition to the "on" position (without starting the engine). 
• Follow the scanner's instructions to read and then clear the error codes. 

3. Remove the fuse 

• This method is more effective on older vehicles. 
• Locate your fuse box and find the fuse for the Engine Control Unit (ECU) or Engine Control Module (ECM). 
• Use the fuse puller or needle-nose pliers to remove the fuse. 
• Wait for 10-15 minutes, then reinsert the fuse. 

Important considerations

• The underlying problem remains: Disconnecting the battery or clearing the code does not fix the issue. If the problem persists, the light will turn back on. 
• Prepare for smog checks: Clearing the code can reset your vehicle's readiness monitors, which is necessary for passing an emissions test. It may take several days of driving to reset these monitors. 
• Be careful: Do not use a scanner to try and "jump" the diagnostic port. This can damage your car's computer. 

How do I erase a code on my car?

You can erase a car code by using an OBD2 scanner or by disconnecting the car's battery. The scanner method is recommended as it allows you to diagnose the problem first, but you can use the battery method for a quick reset if the cause of the code is already known and fixed. For permanent codes or more complex issues, professional diagnosis is advised. 
This video shows how to clear check engine light with an OBD2 scanner: 54sPhillips VisionYouTube · Dec 7, 2020
Using an OBD2 scanner
This is the recommended method, especially for modern vehicles (1996 and newer). 

1. Locate the OBD2 port: Find the port, which is usually a trapezoidal shape, under the driver's side dashboard. 
2. Connect the scanner: Plug the scanner into the port. 
3. Power on the ignition: Turn the key to the "On" position without starting the engine. 
4. Scan for codes: Use the scanner to read the fault codes. It's important to record the codes so you know what the problem was. 
5. Erase the codes: Use the "Erase," "Clear," or "Reset" function on the scanner to clear the codes. 
6. Verify: The scanner should indicate "no codes" or show a "pass" message. Turn off the ignition and remove the scanner. 

This video shows how to clear engine codes with a handheld OBD2 scanner: 1mJust VladYouTube · Aug 21, 2018
Disconnecting the battery (manual reset) 
This method can work for simple issues but may not be suitable for all cars, especially those with complex electrical systems. 

1. Turn off the car: Ensure the ignition is completely off. 
2. Disconnect the negative terminal: Use a wrench to loosen the nut and remove the black "negative" cable from the battery first. 
3. Wait: Press the brake pedal for about 30 seconds to drain any residual power, then wait for 10-15 minutes to allow the system to fully reset. 
4. Reconnect the battery: Reattach the negative cable first, then the positive one. 
5. Start the car: See if the check engine light has turned off. 
   • Note: Some cars may require a radio or navigation code after the battery is disconnected. 

After erasing the codes

• Fix the underlying problem: Erasing the code is only a temporary fix if the issue isn't resolved. The light will come back on if the problem persists. 
• Complete a drive cycle: After fixing the problem, you'll need to drive the car for a certain amount of time or distance to ensure the computer system recognizes the repair and the code does not reappear. 
• Consult a professional: If the code returns, if the problem is complex, or if the light was for a serious issue, it's best to have a mechanic diagnose the vehicle. 

You can watch this video to learn how to reset a car's computer by disconnecting the battery: 59sLouison Automotive Inc.YouTube · Jul 14, 2021

How do I manually reset my car computer?

On. Now comes the tricky. Part the computer's got to relearn. So start the vehicle. And put it in neutral. Let it run for about 4 minutes in neutral.