How To Reset ECU With OBD2 Scanner (+More Methods)

The Engine Control Unit (ECU) is a crucial component of any modern vehicle nowadays. This little box is the brain of your car, which controls everything from fuel economy to ignition timing.

But here’s the thing: Just like us, this brain can sometimes use a little reset. Maybe you’ve noticed some minor electrical glitches or your car’s performance isn’t quite right.

That’s why today, I am gonna help you to reset your car’s computer so you can make sure that everything that’s going on with your vehicle, functions properly.

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And to be honest, you do not need a mechanic degree in order to perform that process. Simplicity is king especially when it comes to cars.

So let’s dive right into it.

What Is ECU?

Simply said, the car computer is what helps every system in your vehicle like fuel, oil, and air function together as one whole.

Your Engine Control Unit (ECU), also known as Engine Control Module (ECM), has one key role.

To manage the fuel-air mixture within the engine. By adjusting the ratio of fuel to air, the ECU can optimize engine performance, reduce emissions, and improve the fuel economy of your car.

Another crucial role of the ECM, which you should already know, is to monitor your vehicle for any potential problems.

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Let’s give an example – Let’s say you have a low oil pressure or maybe your oil pressure sensor has gone bad. The ECU will trigger your check engine light (CEL) and your oil pressure warning light, which will immediately notify you to turn your car off and inspect the problem further.

That way you not only save money on costly repairs but also minimize the risk of potential car accidents. That’s why your car computer is one of the most important parts of your whole vehicle.

Symptoms of a Failing ECU

There are many symptoms of a failing ECU and it will be hard for me to cover all of them.

However here are a few common ones that can point you in the right direction.

• Check Engine Light – If the CEL appears on your dashboard and there are no stored fault codes, that’s surely a symptom of a failing ECU.
• Engine Misfires – If you can feel the so-called “shaking” in your engine and there are no DTC codes, that’s another symptom.
• Poor Performance – Oftentimes if the ECU is faulty, you can experience poor performance and find it difficult for your vehicle to accelerate.
• Starting Issues – In many cases you can experience problems with starting your vehicle if the ECM is failing.
• Unusual Behaviour – Anything related to your car’s electronics like dashboard flashing, fans turning on when the vehicle is not running, or battery drain can be a symptom of a failing ECM.

Is It Necessary To Reset Your Car’s Computer?

In many cases, it’s not necessary to reset the car’s computer, and it’s not like a magical thing that will fix everything wrong with your vehicle.

However, there are some situations where you might find it helpful with fixing some minor glitches.

Let’s put it simply. Your engine control module (ECM) stores data from the moment the vehicle was built, and sometimes the ECM gets confused by all this stored data in its memory.

In that case, performing an ECU reset can clear all that stored data and help your vehicle perform better.

Here are some reasons why you would want to reset the car computer:

• Fix Electrical Glitches – If you fixed something and the CEL didn’t turn off, resetting the car computer can help.
• Better Performance – Usually, the ECU adapts to your driving habits and the reset can help to forget those adaptations and potentially improve the performance.
• Clearing Error Codes – If you do not have an OBDII scanner, the reset can help you to clear “history” codes.

How to Reset the ECU Manually (3 Methods)

If you need to perform an ECU reset and you don’t have a high-level diagnostic scanner, there are a few different methods that you can try.

So let me break them down for you.

Method 1: Remove a Fuse

The first method will be the fuse box method. Basically, the fuse box of your car is the center that controls all the electronics in your vehicle.

Everything from the heated seats to the smallest sensor is controlled by that box.

Most of the time the fuse box is located under the hood of your car and covered in plastic, but depending on the vehicle you own it may be in the passenger compartment as well.

What we are going to do today is to find the fuse that controls your car’s computer and pull it off. Simple as that.

Here’s a step-by-step guide on how to do this:

1. Locate the fuse box. As I’ve said earlier it’s usually in the engine bay or in the passenger compartment.
2. Find the fuse that is labeled “ECU” or “ECM”. Typically, you can find a legend of each fuse right on the back of the plastic cover that you removed to get to the fuses.
3. Once you’ve found the fuse, pull it off. Be careful to not damage anything while removing it. Usually, in the fuse box, there will be a tiny plastic whose purpose is to help you pull out the fuses.
4. Wait for about 15-30 minutes. This allows the ECU to fully discharge and reset.
5. After that period, install the fuse back into the box.
6. Start the engine and let it idle for a few minutes. That way the ECU can recalibrate itself back to normal operation.

And that’s it. You’ve successfully done an ECU reset.

Method 2: Resetting the ECU without Disconnecting the Battery

On some modern vehicles, you can successfully reset the car’s computer system without disconnecting the car battery.

Here’s the process:

1. Turn the ignition on, but don’t start the vehicle.
2. Press and hold the accelerator pedal for about 15 seconds.
3. While holding the accelerator, turn off the ignition and release the pedal.
4. Wait for about 2 minutes.
5. Start your vehicle and let it idle for a few minutes to allow the ECU to recalibrate.

Keep in mind that this method works only for some makes and models and you should check if your vehicle supports that function. You can do a quick Google search with your car model and see if that’s possible or check your owner’s manual.

Method 3: Remove The Battery Terminals

This is usually the simplest of all methods and you have a higher chance to succeed with it.

Here’s a step-by-step process:

1. Turn off your vehicle and find where your battery is located.
2. Remove the negative battery cable(it should be black). You’ll also need a 10mm or a 13mm socket to do this.
3. Wait for about 15 minutes. This puts the engine control module in “sleep” mode and resets it.
4. Reconnect the negative battery terminal.
5. Start your car and let it idle for a few minutes.

This will also delete any stored DTCs in your engine control module.

You can also check this video:

Resetting the ECU with an OBD2 Scanner (Is It Possible?)

Now that we covered how to manually reset the car computer, let’s see if there’s a way to do it with an OBD II scanner.

Typically when we speak about an ECU reset this refers to the process of resetting the car computer to its “factory settings”.

To make things easier to understand, it’s the same as if you return your phone to the condition you first bought it. The so-called “factory reset”.

What’s bothering my mind is the fact that there’s some kind of misconception in the car world about what’s actually an ECU reset. And as I told you above the real ECU reset is the factory reset.

And by simply clearing the fault codes with a scan tool you are not performing an ECU reset.

To do a proper reset you need a high-level diagnostic software which you can find only in the authorized dealerships. A simple OBD II scanner can’t do that.

However, there are certain situations where clearing the fault codes in the ECM can help you.

• After Repairs – If you’ve done any repairs to your vehicle clearing the fault codes can prevent the check engine light from staying on, after everything is fixed.
• Check Engine Light – If your check engine light (CEL) is on, but you are sure that there are no major issues, clearing the “history” codes can help your car’s ECU not get confused.
• After Installing New Parts – If you’ve installed new parts in your vehicle, especially parts that affect the engine or other major systems, clearing the ECM can help it adapt to these new parts.
• Preventive Maintenance – Regularly clearing the ECM can be part of your vehicle’s preventive maintenance routine.

How to Reset ECU with OBD2 FAQs