Turn off the check engine light without a diagnostic scanner

Your check engine light is on. You want to turn it off but don't know how and don't want to go to a mechanic. It is entirely possible to clear the check engine light without a diagnostic scanner.

Before resetting the fault code that appeared on your car, it is important to understand the cause of the issue. If the warning light indicates a fault that requires a mechanical repair and the repair is not carried out, the light will turn back on immediately.

Find the cause before clearing the check engine light

Causes of the warning light: fault codes

The warning light on your car's dashboard indicates that there is a problem with your vehicle. The issue can come from various components and indicate different faults:

• Airbag system faults: the airbag warning light turns on
• Engine faults: the check engine light turns on
• ESP system faults: the ESP warning light turns on
• ABS system faults: the ABS warning light turns on
• Etc...

How to determine what is causing the check engine light to turn on?

The fault detected by the vehicle’s onboard computer is stored in the ECU. For example, if the check engine light turns on, it means the engine control unit has detected a malfunction.

It is not possible to determine the exact fault without connecting a diagnostic scanner to the car’s OBD port. The fault code is only stored in the ECU.

However, it is still possible to clear the check engine light without a scanner by following the steps below.

Warning: If the underlying issue that triggered the check engine light is not fixed, the light will turn on again immediately. This method does not erase the fault code.

How to erase the check engine light without a diagnostic scanner

Disconnect the battery

This method works for all car brands: Renault, Peugeot, Citroën, BMW, Volkswagen, Ford, etc.

1. Park the car in a safe, level area. Engage the handbrake and open the hood.
2. Disconnect the black negative (-) battery cable. Use a simple wrench to loosen the clamp on the battery terminal.
3. Disconnect the red positive (+) battery cable. Under no circumstances should the negative and positive cables touch.
4. After disconnecting the battery cable, turn the ignition on and off 3 to 5 times.
5. Press the horn and hold it for 30 seconds to 1 minute to drain all stored electrical energy from the ECU capacitor. The horn is connected to the thermal circuit, which is why it can be activated regardless of the key position. When the battery is disconnected, pressing the horn helps discharge all electricity from the ECU.
6. This step is optional, but it is recommended to wait another 10 to 15 minutes before reconnecting the battery.
7. Reconnect the battery cables, starting with the red positive terminal, followed by the black negative terminal. Ensure the clamp is fully tightened.
8. Turn the ignition on and check if the check engine light is still illuminated. Start the engine and let it warm up. At this point, the check engine light should turn off.

Below is a video tutorial showing how to turn off the check engine light without a scanner.

Clear the check engine light using your computer

If this method does not work on your vehicle or if you prefer a simpler approach, the best solution is to get a diagnostic scanner. By using a Klavkarr scanner, you can clear your check engine light in just a few simple steps:

• Connect your diagnostic scanner to your car’s OBD port.
• Launch the EOBD-Facile software installed on your computer.
• Go to the "Diagnostics" tab and click "Read".
• Check if a repair is needed for the detected fault.
• Click "Clear".

You have now cleared the detected faults and turned off the check engine light on your dashboard. Watch the video tutorial below for more details.

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