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How to Handle the Check Engine Light: Tips & FAQs

Updated at 15 Feb, 2022

— Why's your check engine light on? Delve into causes with our guide. From easy fixes to expert advice, drive confidently with informed decisions.

How to Handle the Check Engine Light: Tips & FAQs

In this guide on "How to Read and Reset Fault Codes From Your Car", we dive deep into the intricacies of reading and understanding fault codes. Plus, we'll discuss how you can couple these codes with triggers to automatically send out alerts.

When a vehicle's malfunction indicator light, commonly known as the check engine light, illuminates on your dashboard, it can cause confusion and concern. The Check Engine Light, a critical dashboard light, is a warning signal that activates when the vehicle's computer perceives an engine problem or an issue with its emission control systems. This might be due to reasons ranging from a loose gas cap or faulty oxygen sensor to issues with the catalytic converter or the mass airflow sensor.

An illustration of a check engine light indicator on a car dashboard

Ignoring this engine light might reduce your fuel economy and lead to larger issues that require costly engine repairs. It's essential to address it immediately.

But there's good news: with the right tools, like the AutoPi System, you can often diagnose and sometimes even resolve the error codes tied to the check engine lights yourself. This means potentially saving on hefty mechanic bills.

In the example guide below, we will use the AutoPi TMU CM4.

Reading error codes

While on the road, the AutoPi TMU device diligently logs all diagnostic trouble codes (DTC), along with a timestamp and the GPS position. You'll have insights into where a engine issue surfaced and when it resolved, eliminating those frustrating visits to the mechanic where "no issues could be found."

An interpretation of a map showing diagnostics codes

All this data is beautifully mapped on your trips page, ensuring easy oversight. One of the standout features of the AutoPi TMU device is its ability to give detailed descriptions of each error code, its severity, and potential solutions. If, for instance, your check engine alert turns on during a live trip, the specific error, its severity, and potential resolutions are displayed on your dashboard. This is invaluable when a sensor, whether it's an oxygen sensor or another component, might be loose or malfunctioning. Such information can guide your mechanic to a quick and accurate solution.

An example of diagnostics shown in widget

Higher severity faults can be prioritized, while you can deal with less pressing issues at your discretion.

Resetting error codes

At times, you might be equipped to fix the error. This could be a simple fix, like tightening a fuel cap or replacing a spark plug. In such cases, you can clear fault codes or proceed with resetting codes directly from the AutoPi Cloud. While the error details remain on the dashboard, they're marked as cleared and, naturally, won't display in the vehicle. If you ever pondered how to reset codes on car, this device simplifies the process.

However, a word of caution: resetting codes doesn’t mean the root problem is resolved. It’s essential to investigate every warning light and engine light seriously. When unsure, it's always best to seek professional help from an auto repair shop.

To further enhance your understanding or to delve into other features of the AutoPi IoT platform, feel free to get in touch with us. We're here to ensure your vehicle performance remains optimal, and those daunting check engine lights are addressed accurately and swiftly.

FAQs about Check Engine Light

Resetting the check engine light (CEL) can be done in a few methods:

  1. Using an OBD2 Scanner:
    1. Plug the OBD2 scanner into the OBD2 port, usually located under the dashboard on the driver's side.
    2. Turn on your car's ignition to the "On" or "Run" position but do not start the engine.
    3. Follow the scanner's instructions to navigate to the "Read Codes" option.
    4. Review the error codes for any needed repairs.
    5. Once you've addressed the issues or if you just want to clear the light, navigate to the "Clear Codes" or "Reset" option on the scanner.
  2. Battery Disconnect Method:
    1. Turn off the vehicle and locate the car's battery.
    2. Disconnect the negative terminal (usually the black one) for 15-20 minutes.
    3. Reconnect the terminal. This will reset most electronic systems in the car, including the check engine light. However, note that if the issue hasn't been fixed, the light will likely come back on after some driving.
  3. Address the Issue:
    1. Sometimes, simply addressing the problem that triggered the check engine light, like replacing a faulty gas cap, will turn off the light after several drive cycles.
  4. Visit a Mechanic: If the light continues to stay on or frequently reappears, it's recommended to see a professional mechanic for a more thorough diagnostic and appropriate solution.

  5. Note: While it's possible to reset the check engine light, it's essential to first understand why it turned on. The CEL is an indicator of potentially significant underlying issues, and simply resetting it without addressing the root cause might lead to more severe problems down the road.

The check engine light, often represented as an engine icon or the words "Check Engine" on your dashboard, is a warning signal that the vehicle's onboard computer has detected a potential issue with the engine or its emission control systems.

The light looks exactly like the image shown above.

If your check engine light is on, it indicates a potential problem, which could range from minor issues like a loose gas cap to more serious concerns like a malfunctioning catalytic converter. If it's flashing, it's a more urgent sign that there might be a severe engine misfire, which can damage the catalytic converter.

First, check if your gas cap is tight, as this is a common and easily fixable cause. If the light remains on, it's advisable to get your vehicle checked by a professional to diagnose the issue. If it's flashing, reduce driving speed, and seek immediate attention.

The easiest method to reset the check engine light is by using an OBD-II scanner. However, certain vehicles allow you to reset it without a scanner by, for example, disconnecting and reconnecting the battery. Remember, simply clearing the light doesn’t mean the underlying issue has been resolved; always investigate the root cause.

Yes, for some vehicles, disconnecting the battery for a few minutes and then reconnecting it might reset the check engine light. However, this method might not work for all cars, and it's always best to address the root problem rather than just resetting the light.

Remember that while these answers provide general guidance, always consult your vehicle's owner manual or a mechanic for specific advice. - Alexandra Novotná

Article by

Alexandra Novotná

Customer Success / Sales Associate

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