* Check Engine Light Purpose: The check engine light is a signal from the car's computer (ECU) that there's an issue with the emissions system, fuel system, or other critical engine components. It doesn't directly monitor the speedometer.
* Speedometer Cable Function: The speedometer cable is a mechanical component that connects the transmission to the speedometer gauge. It's responsible for physically transmitting the rotation speed of the transmission to the gauge, displaying your speed.
* Separate Systems: The check engine light and the speedometer cable are two completely independent systems.
Possible Reasons for Check Engine Light:
* Oxygen Sensor: A common culprit for check engine lights in older vehicles.
* Catalytic Converter: Issues with the catalytic converter can also trigger the light.
* Mass Airflow Sensor: This sensor monitors the amount of air entering the engine.
* Spark Plugs/Wires: Faulty ignition components can cause misfires and trigger the light.
* Engine Sensors: Various sensors within the engine can malfunction and trigger the light.
What to Do:
1. Read the Codes: The best way to diagnose the issue is to have the check engine light codes read using an OBD scanner. This will give you a specific indication of the problem.
2. Consult a Mechanic: If you're not comfortable diagnosing the problem yourself, take it to a qualified mechanic for inspection and repair.
Important Note: While the speedometer cable isn't directly related to the check engine light, a broken speedometer cable can cause the speedometer to stop working. If your speedometer is not functioning, it's a separate issue that should be addressed.
