When the check engine light in your car comes on, it can be a cause for concern and confusion. However, this warning light is not always an indicator of a major issue with your vehicle. In many cases, it can simply be triggered by a minor problem or even something as simple as a loose gas cap.

Regardless of the reason behind the check engine light turning on, it’s important to address it promptly to ensure the overall health and safety of your car.

In this guide, we will discuss how to reset check engine light and some common causes that may trigger it.

Causes of Check Engine Light On

There are various reasons why your check engine light may come on. Some of the most common causes include:

Loose or Damaged Gas Cap

As mentioned earlier, a loose or damaged gas cap can cause the check engine light to turn on. This is because it can lead to a decrease in fuel pressure, which can trigger the sensor and activate the warning light.

Faulty Oxygen Sensor

The oxygen sensor in your car measures the amount of unburned oxygen in your exhaust system. A faulty sensor can cause issues with your car’s performance and trigger the check engine light.

Malfunctioning Mass Airflow Sensor

The mass airflow (MAF) sensor measures the amount of air entering your car’s engine. If this sensor malfunctions, it can affect your car’s performance and cause the check engine light to come on.

Faulty Catalytic Converter

The catalytic converter is responsible for converting harmful gases into less harmful ones. A faulty converter can lead to a decrease in engine performance and trigger the check engine light.

Bad Spark Plugs or Ignition Coils

Spark plugs and ignition coils are crucial components of your car’s ignition system. If they are worn out or damaged, it can cause issues with starting your car and trigger the check engine light.

Other possible causes may also include more serious engine problems such as a faulty EGR valve, leaking vacuum lines, or a malfunctioning transmission.

How to Reset Check Engine Light? Step By Step

Resetting a check engine light typically involves identifying and addressing the underlying issue that caused the light to turn on in the first place. Here’s a general step-by-step guide on how to do it:

Step 1: Check for Diagnostic Codes

• Use an OBD-II Scanner: Connect an OBD-II (On-Board Diagnostics) scanner to the OBD-II port under the dashboard, usually located near the steering column. This port is often found near the driver’s side footwell.
• Read Codes: Turn on the ignition and follow the scanner’s instructions to retrieve diagnostic trouble codes (DTCs). These codes will help you understand what triggered the check engine light.

Step 2: Address the Issue

• Identify the Problem: Use the diagnostic codes to identify the specific issue. This might be related to the engine, transmission, or another vehicle component.
• Repair the Issue: Depending on the code, you might need to address issues like a loose gas cap, a faulty oxygen sensor, or other mechanical or electrical problems. Consult your vehicle’s manual or a professional mechanic for guidance.

Step 3: Reset the Check Engine Light

• Clear the Codes Using the Scanner: After repairing the problem, use the OBD-II scanner to clear the codes. Follow the scanner’s instructions to erase the diagnostic trouble codes and turn off the check engine light.
• Disconnect the Battery: Alternatively, you can reset the check engine light by disconnecting the vehicle’s battery. To do this:
  1. Turn Off the Engine: Ensure the vehicle is off and the key is removed.
  2. Disconnect the Battery: Use a wrench to loosen the negative terminal on the battery. Remove the negative cable and wait for about 15 minutes.
  3. Reconnect the Battery: Reattach the negative cable and tighten the terminal. This will reset the vehicle’s computer system, including the check engine light.

Step 4: Drive the Vehicle

• Test Drive: After resetting the light, drive the vehicle for a short distance to see if the light reappears. The vehicle’s computer will run diagnostic checks to ensure the problem is resolved.
• Check for Recurrence: If the check engine light comes back on, it indicates that the original issue was not fully resolved or that a new issue may exist.

Step 5: Seek Professional Help if Needed

• Consult a Mechanic: If you can’t clear the codes or if the check engine light reappears frequently, it’s best to consult a professional mechanic. They can perform a more thorough diagnosis and repair.

If you have successfully reset check engine light, congratulations! You’ve taken an important step in maintaining your vehicle’s health and safety.

How to Reset Check Engine Light Without Disconnecting Battery?

While disconnecting the battery is a commonly used method to reset check engine light, it may not always be practical or effective. If you prefer to reset check engine light without disconnecting the battery, here are several methods you can use:

Use an OBD-II Scanner

• Purchase or Borrow an OBD-II Scanner: Obtain an OBD-II scanner, which can be purchased from automotive stores or online, or borrowed from a mechanic or auto parts store.
• Locate the OBD-II Port: Find the OBD-II port, usually located under the dashboard near the steering column.
• Connect the Scanner: Plug the OBD-II scanner into the port.
• Turn on the Ignition: Turn the vehicle’s ignition key to the “On” position without starting the engine.
• Read and Clear Codes: Follow the scanner’s instructions to read the diagnostic trouble codes (DTCs). Once you have noted or fixed any issues, use the scanner’s option to clear the codes and reset the check engine light.

Perform a Drive Cycle

• Repair the Issue: Ensure that the underlying problem has been fixed. A drive cycle involves operating the vehicle under specific conditions to allow the onboard computer to complete its diagnostic checks.
• Follow a Drive Cycle: Drive your vehicle through a series of varied conditions (e.g., short trips, highway driving, idling) to allow the computer to run its diagnostics. The check engine light should turn off once the system confirms that the issue has been resolved.

Use the On-Board Diagnostic System

• Turn the Ignition On and Off: Turn the vehicle’s ignition to the “On” position (without starting the engine), then turn it off. Repeat this process three times. Sometimes this can reset the system, though it’s not guaranteed to work on all vehicles.
• Check the Light: Start the engine and see if the check engine light remains off. If the light comes back on, there may still be an issue that needs addressing.

Check and Tighten the Gas Cap

• Ensure Proper Fit: Sometimes, a loose or damaged gas cap can trigger the check engine light. Make sure the gas cap is tightly secured and in good condition.
• Monitor the Light: After tightening or replacing the gas cap, the check engine light may turn off after a few driving cycles if the issue was related to the gas cap.

Visit an Auto Parts Store

• Ask for a Free Scan: Many auto parts stores offer free OBD-II scans. They can scan your vehicle, identify the issue, and clear the codes for you.
• Follow Up: If the check engine light remains off after the scan, the problem may be resolved. If it reappears, further diagnosis may be necessary.

Perform a System Reset (for Some Vehicles)

• Check the Vehicle Manual: Some vehicles have specific procedures to reset the check engine light that do not involve disconnecting the battery. Consult your vehicle’s manual for any manufacturer-recommended reset procedures.
• Follow Instructions: If applicable, follow the manufacturer’s instructions for resetting the check engine light.

Using these methods, you can often reset check engine light without the need to disconnect the battery, but make sure to address any underlying issues to ensure the light stays off.

FAQs on How to Reset Check Engine Light

How long does it take for reset check engine light?

The amount of time it takes for reset check engine light varies depending on the vehicle and the method used. It may turn off immediately after resetting, or it may take several driving cycles.

Will disconnecting the battery clear a check engine code?

Disconnecting the battery will clear any stored diagnostic trouble codes (DTCs) and reset the check engine light. However, this method is not always effective in resolving underlying issues.

Can I pass an emissions test if my check engine light is off?

In most states, your vehicle will fail an emissions test if your check engine light is on. However, passing an emissions test does not necessarily mean that your vehicle is in good condition overall.

Can I still drive my car with the check engine light on?

In most cases, it is safe to drive your vehicle with the check engine light on. However, it’s important to address any underlying issues to prevent further damage and ensure the safety of your vehicle.

Conclusion

Resetting the check engine light can be a simple process that allows you to maintain your vehicle’s health and avoid potential issues down the road. Whether you choose to disconnect the battery or use other methods, make sure to address any underlying problems for a long-term solution.

If you are unsure how to reset check engine light or if it continues to come on, consult a professional mechanic for a more thorough diagnosis and repair.