The Ultimate Hard Battery Reset Guide

Car battery in the engine bay

Do you have diagnostic lights on? Are certain vehicle electronics acting weird? Inaccurate readings or communication issues? A hard battery reset might just be the thing you need.

A hard battery reset won’t replace a good scan tool to find out where exactly the issue is stemming from, but it’s worth doing when you’re having weird electrical issues and need to clear soft codes in order to find out if there’s an actual issue in your car or if your vehicle electronics simply needed to be reset.

How To Do A Hard Battery Reset

  • Remove the battery (don’t just disconnect it) – If for some reason the battery leads slip off and touch the battery, you can potentially fry the ECU and possibly other components
  • Short out the positive and negative battery leads together by making sure they’re in constant contact – You can use jumper cables to short them out if they’re too short to reach each other. *You must remove all batteries if your vehicle has more than one 12v battery*
  • Have it remain in constant contact for at least 30 minutes – to drain all the voltage from the vehicle electronic capacitors
  • Separate the battery leads and re-install the battery
  • Carefully reconnect the battery leads to the appropriate terminals

Why Do A Hard Battery Reset?

All of us own computers. Whether it’s a laptop, desktop, Apple or Windows, most of us have experienced our computer slowing down or not responding as it should. In fact, many users never turn off their computer at all but simply put it to sleep or hibernation mode.

In short, your computer is never fully off and is still running smaller processes in the background constantly. Often simply restarting your computer eliminates weird unexplainable issues. Your car can behave in a very similar manner since most vehicles are basically computers on wheels nowadays.

On a vehicle this means is that performance can become delayed, certain functions start to freeze or trip-up. When you remove the car keys, your vehicle electronics are still being fed 12v from the battery. Certain components need a constant supply of voltage. Consequently, if the voltage dips or exceeds the nominal point, that can cause issues as well.

Performing a battery reset is like restarting your vehicle electronics. Giving them a fresh-start by reverting components to the default state. Here are a few benefits of a hard battery reset.

  • Clears any soft codes stored in the ECU
  • Resets communication between all the vehicle sensors and the computer modules including the ECU.
  • Discharges voltage from electronic capacitors throughout the vehicle which allows for a hard system reset
  • Helps determine if there is a vehicle circuit issue or if the vehicle just needed to be reset

It’s important to note that electronic capacitors store voltage to supply and feed vehicle circuit boards. If there is an electrical issue a hard battery reset will help in your diagnostic troubleshooting by reverting your vehicle to its default state.

Internal Capacitors
Internal Capacitors

Hard Battery Reset vs. Diagnostic Scan Tool

A hard battery reset won’t replace a handy scan tool even though on the surface they both can clear the codes. However, when both are used together it can help you eliminate a lot of time and frustration trying to figure out what’s causing your electrical issues.

By doing a hard reset, you’re essentially wiping the slate clean. After you’ve done this, proceed to scan the vehicle and search for any faults. If there is a hard code it’ll either return immediately or after driving it for a few miles or so.

It’s very similar to when you restart your computer and run important software to help you eliminate viruses and spyware. The same concept can be applied to cars. Both have their useful purposes but when they’re used together, it can certainly help speed things up.

Most vehicles will respond to universal scan tools. A cheaper and simpler scanner can help troubleshoot the check engine, but you’ll need a more expensive scanner to scan other computer modules if they’re not working correctly. I’ve listed my favorite scan tools here.

A diagnostic scan tool will show you the exact trouble codes. A simple online search of that code should tell you what exactly that code means in detail and possible solutions to fix it. Some scan tools have service bulletins and suggestions on the scanner itself which is quite helpful.

Diagnostic Lights
Diagnostic Lights


Hard battery resets don’t have to be performed regularly and should be done with caution. It’s a good procedure to do when you don’t have access to a scan tool or simply need to reset all the sensors. It doesn’t take too long to do and when done correctly, it can help you avoid headaches trying to figure out where the electrical gremlins are.

Have you ever needed to do a hard battery reset, if so, when?

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Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

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