Why and How To Reset Car Computer: A Complete Guide

A problem in the engine can cause your vehicle to incur damage at a major level. This issue is usually caused by the computer of the car, also commonly known as the ECM. You can reset the whole computer just how you reset your phone when it’s prone to damage at times like this. But you might ask, why and how to reset the car computer?

The ECM or the car computer performs some of the most important functions like- checking the oxygen to fuel ratio, tracking idle speed, controlling the valve timing, etc. When these components face an issue, it can cause damage to the engine. Hence, it’s recommended to reset the ECM. And you can reset it in a bunch of ways.

So, if you want to learn more about how you can reset the ECM and why you should reset it, keep an eye on this article as I’ve highlighted all the details that will help you.

What is a Car Computer and What Does it Do?

If there’s a brain inside your car, that would be the ECM or the Engine Control Module. It works as the computer of your car by storing long-term data inside its term memory.

The ECM controls the other modules to make your vehicle perform at its best by learning everything about your driving habit.

The ECM performs several functions that ensure the smooth operation of your vehicle. These are:

  • Checks the oxygen to fuel ratio for which, it knows everything about the coolant temperature to the proportion of oxygen.
  • Tracks idle-speed
  • Controls the variable valve timing
  • Increases the power by controlling the ignition timing
  • Manages emissions and fuel economy of the engine
  • Gather useful data by using different sensors
  • Ensures low emissions and best mileage

Why You Should Reset Your Car’s Computer

Your car’s engine is nonfunctional without the ECM. It plays an essential role by reading the behavior of the engine.

The ECM is called the car’s computer as it calculates the data of your engine sensors and tracks data simultaneously. It stores trouble codes, which helps to identify the part of the engine that needs repair.

And so, all these functions can stop when there’s an issue with the ECM. Thus, you won’t be able to enjoy the true capabilities of your car.

A quick solution to this problem is to reset your ECM. This procedure will erase its long-term memory, which holds all the trouble codes and faulty data. As a result, the data turns into default and ensures the smooth functioning of the ECM.

Many people tend to change the battery of the engine as a solution. But even after replacing a battery, there might be a need to reset the ECM.

What are the Symptoms of a Failing Car Computer?

When there’s an engine failure, it’s usually due to a faulty car computer. And the failure of this important component will put your car at heavy risk.

So to stay cautious, you should always look out for signs that might indicate these issues.

Some of the common symptoms of a failing car computer are:

Check Engine Light

If the check engine light continuously flickers or stays turned on, there’s a high chance your car’s computer isn’t working. When the computer fails to record a problem with its components, there could be an issue with the ECM.

Burnt Smell 

Whenever you come across any burning smell, always investigate your ECM first. This is one of the common symptoms that can be noticed when there’s an issue with the ECM for heat and overload.

Engine Issues 

You might experience engine issues like- poor timing and acceleration, decreased fuel economy, low efficiency, etc. The performance of an engine significantly lowers when there’s a malfunctioning ECM.

Unsteady Behaviour

The engine of your car can misfire, jerk, and stall suddenly. This unstable behavior can be seen when the computer of your car has problems.

How To Reset Car Computer?

Resetting the car’s computer will restore its default setting and clear the issues of your car. And the fun part is, you don’t need a mechanic or a professional as you could do it yourself.

There’re three ways you can reset the car computer yourself. They are - reset without disconnecting the battery, reset after replacing the battery and reset using a code scanner.

How to Reset Car Computer Without Disconnecting the Battery

To reset your car computer without disconnecting the battery, you will need a couple of equipment– a code reader and fuse puller. Instead of fuse pullers, you can also use a pair of pliers. So, the process is-

  • Locate the fuse box that has various fuses and corresponding amperage.
  • Use the fuse puller to remove the fuse and pull fuses named ‘back-up’ with 7.5A.
  • Locate fuse named ‘ECU’ and pull out with 15A.
  • Keep the fuses disconnected for 10 minutes and then reinstall them with the ECU.
  • Put the fuse cover back and test your care by driving it for a few minutes.

Keep in mind to see whether the check light engine illuminates or not. If the light stops, then your car is as good as new.

The Process to Reset Car Computer After Replacing Battery

Replacing the battery might seem like a solution. But, the ECU might still need resetting. So, After replacing the battery, you can reset the car computer by disconnecting the battery.

You’ll need a battery wrench, insulating tape, or cable tires to start this procedure. Don’t forget to turn off the engine before starting. Here’s how you do it.

  • Spray on the battery to remove corrosion and terminals.
  • Disconnect the negative and positive battery cables by a combination wrench.
  • Hold the positive cable against the end of the negative cable in a way that won’t touch the battery. And bind them with insulating tape.
  • Wait for 5 minutes for the old data to get erased.
  • Test it out by driving for 10-20 minutes.

The procedure will be successful when the check light engine isn’t on after the test drive.

How to Reset Car Computer Through a Code Scanner

The OBD (On-board Diagnostics) code scanner can be used on all vehicles made after 1996. You can either purchase it or borrow it from a friend or family. The process goes:

  • Locate the port where you can insert the OBD scanner.
  • Connect the cord linked to the scanner to the port.
  • Put the key to the ignition and turn the switch of the vehicle on. Don’t start the car whatsoever.
  • Turn off the car’s accessories when the lights on the dashboard turn on.
  • Press ‘Read’ to get access to the check engine light code.
  • Record the code that appears as it will represent the required repairs of your vehicle.
  • Press the ‘erase/clear’ button and wait to see a ‘No code’ signal.
  • Turn off the car and disconnect the scanner.

After taking all the steps, make sure the check engine light doesn’t turn on– that would mean it worked.


Resetting the computer of a car can save the vehicle from facing further failure. Without this computer, the normal functions of your vehicle will stop. Hence why you must know how it’s done.

That’s why I’ve answered everything about why and how to reset a car computer. Now, you can reset your car’s computer yourself when there’s an issue with it.

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