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Why is the Engine Light ON?

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If the light comes ON and stays ON, the On-Board Diagnostic (OBD) system has detected a problem. The OBD system monitors the vehicle performance and regulates engine speed (RPM), fuel mixture and ignition timing.

Related: What is OBDII?

Engine Light common causes:

Loose or damage gas cap: The gas cap is used to hold and maintain pressure in the gas tank. Loose or damage gas cap will cause gasoline fumes to escape the gas tank to the atmosphere. Re-tighten or replacing the gas cap will fix problem.

Damage catalytic conveter: The catalytic converter helps convert harmful exhaust gas into a more environmental friendly gases. Deterioration of the catalytic converter will trigger the engine light. Replacing the catalytic converter will fix the problem. If the catalytic converter is not totally damage, using high octane gas for a couple of weeks may fix the problem.

Damage Oxygen (O2) Sensor(s): The oxygen sensors measures the amount of unburned oxygen exhausted by the engine. Replacing the oxygen sensor will fix the problem.

Engine Light other common causes:

How to read engine codes

An OBDII scanner is the best alternative to read codes, although there some manufactures have indication on how to read the code using the engine warning light, using an OBDII scanner is more accurate.

How to clear or erase engine light

After problem is fixed, the engine light can be cleared with an OBDII scanner or by disconnecting the car battery for more than 30 minutes.

Related FAQ

- What is OBDII?
- How does the OBDII works?
- Why is the Engine Light ON?
- Is the OBD system working correctly?
- What does it mean if the Service Engine Soon or Check Engine light is blinking?
- What does it mean if the Service Engine Soon or Check Engine turns on while I'm driving?
- What should I do if the Service Engine Soon or Check Engine light stays on?
- What is Bank 1 and Bank 2?
- What is ECM?
- What is PCM?

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