Why it might be on despite regular servicing:
* Sensor Issues: Oxygen sensors, mass airflow sensors, and other sensors can fail even with regular maintenance. These sensors are crucial for the engine's performance and the computer uses their data. A failing sensor will trigger the light.
* Gas Cap: A loose or faulty gas cap can cause a small leak, triggering the SES light due to evaporative emissions system problems.
* Spark Plugs/Wires: Worn spark plugs or faulty ignition wires can cause misfires, leading to the light. While spark plug replacement is part of regular maintenance, they can sometimes fail prematurely.
* Catalytic Converter Issues: These components can degrade over time and cause the light to illuminate. This is a more expensive repair.
* Other System Malfunctions: Problems with the air conditioning system, transmission, or other components can sometimes trigger the light.
What you should do:
1. Get the code read: The most important step is to have the OBD-II diagnostic trouble code (DTC) read. You can do this with a relatively inexpensive OBD-II scanner from an auto parts store or have a mechanic do it. The code will provide a clue as to what's causing the light.
2. Don't ignore it: Continuing to drive with the SES light on could lead to further damage and more expensive repairs.
3. Address the underlying issue: Once you know the code, you can address the specific problem. Sometimes it's a simple fix (like tightening the gas cap), other times it requires more extensive repairs.
Regular servicing is important for preventative maintenance, but it won't prevent all potential problems. The SES light is a warning system – get it checked out promptly to avoid more significant issues.
