How to Reset a Check Engine Light (5 Best Methods)

Your check engine light typically comes on when there is a problem with your emission control system or another computer-controlled system in your vehicle. The light generates a code that can help you narrow down the problem so you can get it fixed. You may also need to manually reset a check engine light after making repairs if the code doesn’t clear automatically.

The best way to reset a check engine light is to use a code scanner. However, if your vehicle was manufactured before 1996, you can simply disconnect the battery to reset the light.

How to reset Check Engine Light

The easiest way to reset the check engine light is by using an OBD2 scanner. But if you do not have one available, you can often do it without one.

check engine light

Here are some different ways how you can reset your check engine light:

1) Use an OBD2 Scanner

“OBD” stands for “On-Board Diagnostics”, and OBD-II scanners are suitable for all vehicles made after 1996. Purchasing a code scanner can be costly, so it’s better to borrow one unless you plan on using it frequently.

OBD2 Scanner

Follow the below-given steps to reset the check engine light using a scanner:

  • Note that vehicles made before the 1990s may not have an OBD port under the dash. If they do, it may be an OBD-I port rather than an OBD-II port, and you will need a different scanner.
  • Plug the scanner into the port under the steering column: Modern vehicles have ports specifically designed for OBD scanners. Look underneath the steering column to find the port, then connect the cord attached to the scanner to the port. Refer to your vehicle’s manual if you cannot find the port.
  • Put your key in the ignition and switch the vehicle to “on.” Do not start the vehicle. Once the lights on the dash come on, turn off all the vehicle’s accessories, like the radio. Then, press the “read” button on the scanner to access the check engine light code.
  • The code will be a series of letters and numbers. Record all of the codes so you can figure out what they represent and make the necessary repairs to your vehicle.
  • Some scanners will define or explain the codes, while others will not. If you don’t get a definition, look up the code in the owner’s manual or online.
  • Clearing any codes present will turn off your check engine light temporarily. After pressing “erase/clear” and waiting until you see a “no codes” message, you can turn off your vehicle and disconnect the scanner. However, erasing the codes does not fix the problem. If your check engine light comes on, it’s best to take your vehicle to a mechanic to get it professionally diagnosed and repaired.

2) Disconnecting the Battery

The best way to reset the check engine light without a scan tool is by removing the battery terminal for 30-60 seconds. This will reset the engine control unit in many car models.

Disconnecting the Battery to reset the check engine light

  1. First, remove the negative car battery terminal. Then try to drain any available electricity present in the car’s capacitor by pressing the horn for around 20-30 seconds or turning on the lights.
  2. Once the electricity is disconnected, leave your car for 10-15 minutes.
  3. After this short time, reconnect the battery terminals, make sure they are well tightened to avoid any possible sparking, and then switch on your car.
  4. If your car gives that same check engine light after restarting, then it means there is some serious problem in your car, or your car stores the codes anyway. In such a case, check the codes with a scanner is highly recommended because some car models will not reset the codes by removing the power.

3) Let It Clear Itself

The check engine light may illuminate for a malfunction which is temporary. This type of fault may self-correct over a short length of time. Or it may simply not repeat. And sometimes, you can be patient and wait for this to happen.

Three engine start and stop cycles are required for self-correction to turn the CEL off.

check engine light resetting without scanner

A benefit of this particular OBD2 behaviour is that you may not have to race to the shop the instant the CEL comes on. If the car continues to run normally when the CEL lights up, you can delay for three driving cycles and possibly avoid a needless trip to the mechanic.

When the CEL comes on, the engine begins to run roughly, or driving behaviour becomes noticeably bad, an immediate trip to the shop for help would be well advised.

It’s important to note here that even if the CEL turns off, the fault code will remain stored in ECU memory to benefit any necessary future diagnostics.

4) Turning the Ignition On and Off 

Switching the ignition on and off is also one method of hard reset without disconnecting batteries.

Turning the Ignition On and Off

  1. Put the keys in your ignition and turn your ignition on and off consecutively after a second in each step.
  2. Once it is done, see if the engine check light is still coming on or not.
  3. If the check light is off, you are ready to go, but if it is still coming on, get ready by reading the codes with a scanner instead.

Read More: Causes of Check Engine Light Flashing 

5) Pulling Off the Fuse and put back

One possible way to get your check engine light to go off is to pull off the engine control unit’s fuse and then put it back again. Although this won’t solve the problem in newer cars, it may solve the problem in older cars, which is easy to try.

Pulling Off the Fuse

Check your repair manual to find the fuse to the engine control unit.

Solid vs Flashing Check Engine Light

The check engine light can display a malfunction in three different ways. It can turn on and stay on, indicating the likelihood of a serious problem. But if it occasionally flickers on and off as you drive, this may tell you that there is an intermittent problem.

For example, the engine could occasionally be misfiring. Fault codes will be set if the light flickers, and you should use an OBD2 scanner to check for codes or get professional help soon if such check engine light behaviour continues or recurs.

The most serious condition will be a steadily flashing CEL. On-off, on-off, and so forth. Should this kind of display be noted, you should pull to the side of the road and shut off the engine.

In some cases, continuing to drive with the CEL flashing steadily can result in costly damage to your engine and/or related systems. But in other cases, a flashing CEL and shaking may indicate a cylinder misfire.

FAQ Section

What If the Check Engine Light comes back On?

The CEL will come on when a serious malfunction occurs. This is known as a “hard fault”. Such a fault will not just go away. So, if the OBD2 system has detected such a problem, and you have turned the CEL off by whatever method, it will just turn back on.

This will most likely occur the next time you start the engine. You cannot get rid of a Check Engine Light that’s related to a serious malfunction, such as if your catalytic converter or O2 sensor has gone bad.

How do you reset the check engine light without scanner?

To reset a check engine light without a scanner, disconnect the negative battery cable and wait a few moments. This will reset the diagnostic system in your vehicle, and if the underlying issue has indeed been resolved, the light should go off immediately.

How long before the check engine light comes back on after reset?

In general, you will need to drive between 45 to 100 miles after you clear your car’s computer. Hopefully, this will get rid of the check engine light once and for all.

What happens when you reset the check engine light?

When the check engine light comes on, a trouble code is stored, and freeze frame data is stored. A trouble code lets us know which computer test failed. The freeze frame data shows us the data the computer saw at the time of the fault. Resetting the check engine light erases all of this data.

Does disconnecting the battery clear codes?

Disconnecting the battery will clear the error codes and reset the check engine light.

What happens when you clear codes on a car?

When a code clears, you know that the vehicle has been restored to good working order. However, there could be occasions when clearing the codes manually is part of the repair process. For example, a check engine light can be triggered when the gas cap isn’t tightened correctly.

Is it OK to drive with the check engine light on?

The illuminated check engine light is a sign you should stop driving and have your car looked at by a mechanic as soon as possible. Use your best judgment on whether to call a tow truck or drive yourself to a nearby repair shop.

Can bad gas cause a check engine light?

If your check engine light comes as a symptom of bad gas, try filling up at a different gas station moving forward. There’s a chance that after using a tank or two of new, quality gas in your car, the check engine light will turn back off. It is never a good idea to ignore a check engine light for long.

Is it illegal to remove the check engine light?

It’s called fraudulent concealment, and it is illegal. Many states will allow punitive damages. This car dealership should count itself lucky that you discovered this problem before it caused any personal injuries.

How long does it take for the check engine light to reset?

If you are sure you have fixed the problem, it takes around 10-30 successful cycles before the check engine light disappears. One process is one cold-start until the engine is warm.

Can the check engine light come on for no reason?

The check engine light can come on for many reasons. For example, something as simple as a loose gas cap can trigger the warning. And major problems, such as faulty MAP sensor or low engine oil, can also turn on the light.

Leave a Comment