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Why Resetting Your Car Computer is Important After a Battery Change?

November 17, 2021
Quick Help From The Internet

Why Resetting Your Car Computer is Important After a Battery Change?

You may be having issues with your car’s Electronic Control Module or battery, or maybe the electrical system. If you’re tired of trying to find the problem and want to sell your car, at Acres Auto, you can sell your car online or sell your car for cash. You can even sell a wrecked car.


The need of resetting your car computer after a battery replacement is very important. A car computer reset is a common way to do an ECM (Electronic Control Module) reset, which helps you to identify that the car part replacements you make, are absolutely necessary if the check engine light remains on.

A lot of people believe that resetting a car computer after a battery replacement will magically fix their check engine light issues. However, that is far from the case. The check engine light is an indication that a sensor, or multiple sensors, is either out of specification, malfunctioning or faulty. They have to be tested before being fitted again, or else driving the car with a faulty sensor could be dangerous. This calls for a diagnostic test, run by an external code scanner that is connected into the car through a plug, located mostly at the bottom of the steering wheel. A check engine light may only be erased, or ignored if a full diagnostics test is run and the problem has been worked upon. However, this leads a lot of people to

As we mentioned before, in a lot of cases, the check engine light still comes on after a sensor has been worked upon. The reason for this could be an electrical issue in the vehicle. However, before working on any electrical issue, it is better to do a complete ECM reset. This will give you a definite answer on whether any parts need replacement or not. In the case where the problem seems to persist or grow, then it’s best to look for an online towing service and get your car checked with a nearby mechanic.

An ECM reset is best done with an external code scanner. Nowadays, scanners have become common and are available for very cheap prices. They’re also Bluetooth configured. However, in a lot of vehicles, simply disconnecting and reconnecting the batteries would be enough. Once the battery is reconnected, start your car and drive it for at least 10 to 15 miles. That gives the ECM enough time to detect if the problem still persists or whether it’s fixed. Another valid reason for resetting the car computer is so that the ECM can identify the new parts when a part replacement is done. The ECM can then store the data and start functioning with the new part.

All ECU (Engine Control Units) can be reset easily and should be reset as per the manufacturer’s recommended guidelines. This ensures your car computer to have enough time to easily learn the replacement component codes.

After the installation of new parts in your car, you then reset your computer so that the ECU can learn about the new parts and their codes, and then store its data to function properly. However, before resetting the ECU, it is important to check whether the battery cables are perfectly fine or do they face issues and whether you have a backup power source like a jump starter.

Important Tips for When You Reset Car Computer

A car battery disconnection can and will result in a multitude of results. So it’s always important to consider a few things before you make the move. Here’s a list of a few things you need to note down when resetting your car computer:

  1. If the battery is removed when the car is switched off, make sure that the battery voltage is maintained to the Powertrain Control Module (PCM). However, never, in any case, remove the battery when the engine is running or the ignition key is switched on.
  2. Your car battery does a lot more than just provide electricity. It controls the AC spikes and transients to the ground. When the battery is removed, these spikes and transients travel all around the car’s circuit. This may damage a lot of the electrical and electronics components in the car.
  3. In any car with computerized engine controls, removing the battery causes the PCM to forget its adaptive memory settings. These memory settings are the ones that the PCM has learned with time, including the fuel mixture, transmission change points, and other functions.
  4. The car may experience problems starting the next time. This could be due to engine faults with faulty fuel mixtures or a damaged ignition system because of voltage spikes.
  5. The loss of important features such as window defoggers, air conditioning, heating system, headlights, and backlights
  6. Inaccurate and untimely warning lights
  7. Your alternator could become faulty, after which you would have to buy alternators or look for a used alternator to get a cheap replacement

How the PCM Comes Into Influence

The PCM is a component that consists of the ECU and the Transmission Control Unit (TCU). The PCM is technically the brain of the engine control system. It controls over 100 factors of a car, including air-fuel mixture and transmission control levels. Removing the battery puts the PCM in a factory reset mode, forcing it to forget all its learned memory. This means when the PCM comes back online, the car will initially run differently. This is because the PCM will need time to relearn the basic levels and settings at which the car operates. Until the PCM relearns the settings, the car may run on very low or very high RPMs even when idle, gear shifting timing would be changed and uneven. An unlearned PCM or a factory reset PCM can also cause malfunction to the airbag system.

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