To find out *what* is causing the light, you need to get the diagnostic trouble codes (DTCs) read. This can be done a few ways:
* OBD-II Scanner: Buy a relatively inexpensive OBD-II scanner from an auto parts store. These plug into a port usually under the dashboard, and will display the DTCs. This is the most common and affordable method.
* Auto Parts Store: Many auto parts stores will read the codes for free. They can then advise you on the potential problem and cost of repair.
* Mechanic: A qualified mechanic will be able to diagnose the issue accurately and perform the necessary repairs. This is the most reliable but often most expensive option.
Possible causes for the SES light on a 2003 Cadillac DTS are numerous and range from minor to major issues, such as:
* Loose or failing gas cap: A simple, inexpensive fix.
* Oxygen sensor problem: Relatively common and can affect fuel efficiency and emissions.
* Mass airflow sensor issue: Affects air-fuel mixture and can impact performance.
* Catalytic converter problems: More expensive to repair or replace.
* Ignition system faults: Can lead to misfires and poor performance.
* Other sensor failures: Various sensors throughout the engine monitor different aspects of its operation.
Ignoring the SES light is not recommended. Driving with a problem could lead to further damage, reduced fuel economy, increased emissions, and potentially unsafe driving conditions. Get the codes read as soon as possible to identify the issue.
