How Long Does it Take for a Car Computer to Reset

The computer also known as the brain of the engine controls all systems in the car. Due to some problems in the car and its after effect, there may need to rest of the car’s computer.

There are various ways to reset a car’s computer with each method having a different reset time. Irrespective of the various methods, how long does it take for a car computer to reset?

It takes a car computer between 10 – 20 cycles, 30 and 45 minutes, or 100 miles to reset.

Can a Car Computer Reset Itself?

A car computer can reset itself, however, this can only happen when the problem has been fixed.

Some people may decide to manually reset the car’s computer, this is also possible but you should know that resetting the computer when the problem hasn’t been fixed will only cause the check engine light to come back on.

The only way to get the light off and have the computer reset itself without coming back on is to fix the problem.

How Long Does It Take for a Car Computer to Reset?

The length of time it will take a car computer to reset depends on the car, this is because some cars have more advanced systems than others.

For a car computer to reset itself, all the systems and sensors in the car must first be evaluated to ensure they are in good condition.

While the evaluation is going on the car must be in motion, therefore, one can say it takes about 100 miles for the car computer to reset. Or about 10-20 successful cycles for the computer to reset and the light to go off.

How Do You Reset a Car Computer?

After a problem in the car has been repaired and the check engine light remains on, it simply means the error code hasn’t been cleared from the computer.

To reset the code and have the light go off, you can either wait for the computer to reset itself or do it yourself.

If you decide to have the computer reset manually, there are a couple of ways to have it done. You can use any of the following methods.

Switching the Ignition on and Off

This method seems like the easiest way to reset a car’s computer. To do this, you simply need to put the car keys in the ignition and turn them on and then off.

This should be done a number of times until the light goes off, if it doesn’t after a couple of attempts you should consider other options.

Give it Time to Go Off

If the light on doesn’t bother you, you can allow it to go off on its own. The car computer is able to reset itself provided the problem has been fixed.

For this to happen, you have to continue driving the car in order for the computer to evaluate the various systems in the car.

Use a Scanner

Another method to reset the car computer is by using an OBD2 scanner. If you are using the scanner, you will need to have the scanner connected to the OBD connector under the car.

Once the connection has been established, you should turn on the ignition and press the ‘read’ button on the scanner. The scanner then proceeds to search and diagnose all codes.

All codes should be noted and decoded by using the owner’s manual. In solving the problem, some parts may need to be changed, and others calibrated. After this must have been done, proceed to erase the code on the scanner then switch off the ignition.

Disconnect the Battery

If you do not want to use a scanner tool to reset the computer, you can as well disconnect the battery.

Start by removing the negative battery terminal, after which you will need to drain available electricity in the car’s capacitator. This should be done by pressing the car’s horn for between 20-30 seconds.

Once this is done, you can leave the car for between 10 – 15 mins. You can then proceed to reconnect the battery terminal and then switch on the car.

If none of these methods works in resetting the car’s engine you should have it checked out.

Pros of Resetting Car Computer

Some advantages of resetting a car’s computer are as follows;

  • Get Rid of Check Engine Light: One of the advantages of resetting the car’s computer is that it helps you get rid of the check engine light. Whatever method you choose to rest the car’s computer will make the check engine light go off.
  • It Improves Fuel Economy: If you have been experiencing reduced fuel economy, try resetting the car’s computer. Resetting the computer is a way to remove all error codes in the system that may be causing the reduction in fuel economy.
  • It May Improve the Car’s Performance: Resetting the car’s computer is a way of improving its performance. With lots of error codes in the ECU, the car may be underperforming.

What Happens if You Fail to Reset Car Computer?

Resetting a car’s computer may be necessary under certain circumstances but what happens if you fail to reset the computer? Here are some things that will likely happen;

  • The Check Engine Light Will Remain On: Although it is possible for a car to reset itself, this is not the case in all vehicles. In some new cars, you will need to manually reset the computer. Therefore, if you fail to reset the computer, the light will remain on.
  • Many Codes on the ECU: The ECU is said to be the brain of the engine. All problems in the car have a code that should be cleared out once it has been fixed, failure to have the computer reset invariably means all the codes will remain in the system. Overloading codes in the system may lead to other problems in the engine.
  • The Engine may Underperform: If you fail to reset the computer it gets overloaded with codes. A lot of codes in the ECU can cause the car to underperform.
  • Reduced Fuel Efficiency: Failure to reset the car’s computer will result in a reduction in fuel efficiency. This is because some uncleared errors will cause the computer to work overtime, which results in excessive use of fuel in the car.


If you have tried all you can to reset the car’s computer but the check engine light remains on, you should take the car to the auto shop so they can have a look at whatever the problem is and fix it.