Check Engine Light After Battery Change (Causes & Fixes):

So you just installed a new battery in your vehicle and now you’re dealing with the dreaded check engine light? If yes, this guide is for you.

Check engine light after battery change means something is wrong with the car computer. It could be that your car computer is malfunctioning or confused following the swap. The check engine light shouldn’t come on after the battery change as the computer ought to learn by itself that a new battery has been installed and reset itself.

The following post sheds more light on why the check engine light comes on after switching to a new battery, how to reset the light on your own, and other helpful related information you need to know.

Why check engine comes on after battery change

Check engine light (CEL) should NOT occur after battery change if it wasn’t there before the replacement (and provided you installed the new battery correctly).

However, if it pops on after the battery swap, it could be pointing out that your ECU (electronic control module) or car computer has an issue. Or your vehicle could be having an entirely different issue that’s not related to battery replacement.

But in most cases, it’s a problem with the car computer. When the computer sees a new battery that gives more power compared to the old weak battery, it will report this as a fault and throw the check engine light.

Gladly, the computers on vehicles are self-learning and usually reset themselves after they learn you have installed a new battery.

Unfortunately, the computer may not always reset itself. And this is when you get the unexpected check engine light popping on the dashboard.

In this case, you’ll have no other option but to clear the error codes manually to make the light go away (more details on how to reset the check engine light after battery change coming up later—keep tuned in).

Remember, however, that the best way to know what’s ailing your car is having its fault codes read.

You can have them read at your dealership or any local auto parts shop. This goes a long way in helping uncover the underlying problem causing the CEL.

If the problem is simply the computer not resetting itself, then you can solve it by resting the check engine light as we have discussed below…

How do you reset check engine light after replacing the battery?

You can easily replace the check engine after battery change on your own, without visiting your dealership or auto mechanic shop. There are several ways you can do this as outlined below.

The first method involves disconnecting the battery and then reconnecting it after around 15 minutes. Simply use a small wrench to help you loosen the bolt on the negative battery terminal.

Let the car sit for at least 15 minutes and then reconnect the cable and be sure to tighten the clamp. Now start your vehicle to see if the light is gone.

If that method doesn’t work, try clearing the light using an OBD-II scanner. Simply connect it to your vehicle’s OBDII port (this is usually located under the steering wheel).

Error codes will be displayed on the scanning tool display. Go to erase option to clear these errors from the system. Now start your vehicle to see if the light is gone.

What if none of the above methods work? In this case, we recommend getting a mechanic to fix the issue causing the light.

Can a bad battery trigger a check engine light?

If you had a bad battery before switching to the new one, then it can also trigger a check engine light.

When the battery is damaged, it can’t supply the correct voltage to the car computer. The computer is then forced to register faulty code for low system voltage which triggers a check engine light.

The good news is that the light usually goes away after you replace the bad battery with a new one. The light doesn’t reset immediately…but it may go off on its own after about 3 drive cycles.

In some vehicles, the light will clear itself off after driving for a while, say 50 to 100 miles.

If the light doesn’t go away, you can manually clear it using one of the methods we discussed previously.

What should you do after replacing car battery to prevent check engine light?

After you make a successful battery swap, you should run your car for about 30 minutes to give the alternator time to charge the new battery.

But this step might not be necessary as new batteries now come with up to 40-80% charge, so you can start driving your car normally after installing them.

Generally, there isn’t much you can do to prevent the check engine light from appearing.  Remember that the car computer and radio will reset following a battery change.

You’ll then have to reset your car computer and radio presets. This will then clear the check engine light if it has appeared after battery change.

Also, if the light was already therefore before the battery swap, you’ll need to give it time to clear itself. Or you can manually clear it using one of the methods we discussed earlier on.

Can a new battery cause check engine light to come on?

Yes, a new battery can cause CEL to come on if it is undercharged (i.e. with a percentage of charge level that’s considered too low for the engine).

The car computer will interpret this as low voltage and report a fault code which then triggers the check engine light.

Let your car run for about 30 minutes to charge the new battery and the light will clear itself off afterward. Or you can try charging the new battery up to 75% before installing it in your car engine.

Some vendors also tend to sell poor-quality batteries. If the new battery you just installed in your car is bad, then the check engine light will also be triggered. The only solution for a bad battery is to get a new one.

If you’re looking for more information on how to address a check engine light, our articles on resolving issues after an oil change and what it means when your check engine light flashes then turns off might be of interest to you. Our article on resolving issues after an oil change offers helpful tips on what to do if your check engine light appears after an oil change. Meanwhile, our article on check engine light flashes then turns off explores the potential causes of this issue and what steps you can take to address it.

FAQs:

1. Do you need to reset the car after changing battery?

If you want to, you can reset your car computer after changing the battery to get rid of the check engine light. The most common ways of doing so include using an OBDII scanner or disconnecting the battery and then reconnecting it. If you get stuck with the reset process, you can have a mechanic or auto parts shop do it for you.

2. Does the check engine light reset on its own after battery change?

Yes, the check engine light can sometimes reset on its own after a battery change. This happens after the car computer restores the sensor’s ability to detect a new battery, causing the check engine light to go off. However, the light may take hours or even a day(s) to go off, so don’t expect it to be instant.

Final Verdict

Getting a check engine light after a battery swap can be stressing experience, especially when you don’t know what caused it. But you need not panic. The light is usually triggered by your car computer getting confused after the battery swap. A malfunctioning computer can also cause the CEL to come on.

You can easily reset the check engine light on your own by using the OBD II scanner tool or by disconnecting the battery and then reconnecting it after about 15-20 minutes. If these tricks don’t work, or if the light comes back on, you should take your car to the mechanic to diagnose the issue causing the light and fix it.