How To Reset Car Computer Without Disconnecting Battery

Reset Car Computer Disconnecting Battery

Disconnecting the battery is not the only way of resetting your car's computer. There are many ways of resetting the engine control unit (ECU) without unplugging the battery terminals.

Resetting your car's computer comes with a lot of benefits, like clearing error codes and fixing unexpected and unexplainable engine behavior. A car computer reset brings your car to its default mode. So how can you reset your car computer without disconnecting the battery?

It's simple! You can reset your car computer without disconnecting the battery by either using a scan tool, removing the car computer's fuse, or simply using the reset button.

Sounds easy, right?

Read on to find out how to use these tools, the precautions involved, and the step-by-step process of how to reset the car’s computer without disconnecting the battery.

How To Reset Car Computer Without Disconnecting the Battery

Most times, disconnecting your car's battery doesn't do the perfect job of resetting your car's computer. Sometimes, it only stops at resetting the close or wiping the radio memory of the car. In the end, the error codes remain.

In this case, you'll need to learn more advanced ways of resetting your car's computer without necessarily unplugging the battery.

Here are five easy steps for resetting your car's battery without removing the battery.

1. Use a Scan Tool

Using a scan tool or an OBDII reader remains one of the most reliable ways of resetting your battery without necessarily resetting the car's computer.

A scan tool like an OBDII reader is a car diagnostic device that can read and erase error codes from your car computer's system. The difference between a scan tool and OBDII readers is the level of technicality involved in both devices.

Scan tools can go as far as offering troubleshooting guides that will help you diagnose and resolve the issue in your car.

To reset your car's computer with a scan tool, you have to do the following:

  • Turn on your car's ignition, but don't start the engine.
  • Connect the scan tool to your vehicle's onboard diagnostic system: You can do this by plugging the scan tool into the OBDII port. The OBDII port is under your car's dashboard, just below the steering column.
  • Turn on the scan tool and select your vehicle's make and model: After selecting your vehicle's make and model, wait for the scan tool to scan your car's system. When properly connected, you can locate the 'read button' for the scan tool to scan and present live data (errors) from your car's sensors.
  • Read and Save error codes: It's true that you only plugged in the scan tool to reset your car's computer, but it's not a bad idea to save the error codes for future reference. You can jot down those error codes in your notebook, then take the codes to a mechanic to aid the process of servicing your car.
  • Erase the codes and confirm your action: You can click the 'erase' or the 'clear DTC' button on your scan tool to clear the error or diagnostic trouble codes from your car's computer. This is just as good as auto-resetting your car's computer system.

When you are done, turn off everything. Turn off the scan tool, unplug it from the OBDII port, and turn off your car's ignition.

2. Use an OBDII Code Reader

An OBDII code reader is similar to a scan tool, but there are limitations to its functionality. OBD2 code readers can only read and erase error codes from your car computer. There aren't many provisions for offering diagnostic reports or tips to address the problem.

Here are easy steps to reset your car's memory with an OBDII reader.

  • Turn on your car's ignition, but don't start the engine.
  • Connect the OBDII reader to your car's system.

Just as you did with the scan tool, plug the OBDII code reader into the OBDII port.

  • Turn on the OBDII code reader and wait for it to connect to your car's computer.
  • Click scan to continue.

Locate and press the scan button on the OBDII reader for it to scan the error codes in your car. You can also decide to read and save the allows you to read codes and note them down for future reference.

A lot of times, the problem with using OBDII readers to reset your car's computer lies in understanding the scan results.

If you can read and understand the codes perfectly, then there's no need for a mechanic. You can easily fix the problems and restore your car's condition to normalcy again.

  • Erase and reset.

When the reader is done scanning, and you're done saving the error codes, you can click 'erase code' to erase the codes. Turn off the reader and disconnect from the OBDII port.

Turn off your car's ignition, and your car's memory should be reset.

3. Remove the ECM fuse

One of the last steps of resetting your car's computer without removing the battery is by removing the fuse. Some drivers pair up this process by disconnecting the battery. That means they remove the fuse box after disconnecting the battery.

You can reset the computer by removing the fuse, whichever side you're on. But this is not just any fuse, but the fuse attached to your engine control module. Removing the fuse is an easy way of resetting the ECU or ECM.

To reset your car's computer by removing the fuse, you have to do the following:

  • Locate the fuse box in the hood of your car.

The fuse is located under the hood inside the fuse box. It might be a bit tricky to locate the ECM/ECU fuse because there are a lot of fuses in the fuse box.

You'll need to confirm with your driver's manual or check the diagram of your vehicle to confirm where the fuse is located. Sometimes, the fuse is marked ECM.

  • Remove the fuse, and don't let it stay out for more than 15 mins.

After removing the fuse, hold and wait between 1 and 15 mins. Replace immediately after the time elapses.

There are a lot of arguments about what will happen if you remove the fuse and hold it out for too long. Although we understand that the circuit will be broken, you don't need to experiment with your car to find out what will happen.

  • Replace fuse.

After 15 mins, replace and reinstall the fuse. Don't forget to cover the fuse box. This should automatically reset your car's computer.

Most times, we wish that there was simply a reset button on cars that can enable you to reset the computer with just a simple click. While this is not available on all modern cars, you must understand that while trying out these steps, high-level precision is required.

Don't forget to leave the fuse out for too long, and do not attempt to fix the error codes from the scan tools or readers if you don't have professional experience.

What does a car computer do?

A car's computer handles the entire electronic and mechanical operations of your car. From monitoring emissions to controlling air conditioning systems, radios, traction control, safety, security, and alarm systems, even your airbags are controlled by the car's computer. The car's computer is a fundamental element of a car that you can't ignore.

How Long Does It Take for a Car's Computer To Reset?

It should take approximately 30 mins or a 50 to 100-mile drive for a car's computer to reset. You must understand that resetting a car's computer doesn't end with unplugging the battery terminals or removing the fuse box.

The car's computer will need to relearn its systems, and the sensors need to work, monitor events, and register results. This will be achieved by taking your car for a slow ride downtown.

Can a Car Computer Reset Itself?

It depends. A car computer will not reset itself if no repairs are made. However, a reset will occur automatically if the error codes are cleared.


You must understand that different advantages and disadvantages are attached to the different methods of resetting your car's computer without disconnecting the battery. Some of these disadvantages can include the cost of buying the tools or even the technicalities involved in operating them.

It is important that you choose the method that meets your needs and budget. Refer to the user's manual when you are stuck, and don't forget to take the car for a test drive when you are done. This will help you decide if the errors were resolved or if they came back after driving for a while.

When you are done resetting your car's computer, don't forget to turn on your car's engine and run the car on neutral and low gear for at least 4 mins each. This will help your car's computer relearn. If the problem persists after following the processes we've listed to reset your car's computer, you should take the car to a professional to help rectify the issue.