Why is my check engine light always on?

Hello everyone. So I m a security professional and I recently purchased the old company Crown Victoria. The car has a few minor problems, but it always turns over, never dies, and performs fairly well. However, the check engine light is always on. It literally never goes out.

The vehicle seems to burn through oil and produces more exhaust than I d expect, but nothing seems actually wrong. The windows, wipers, and hi beams seem to slow down and speed up randomly, however the battery always stays charged and the regular headlights and signals work normally.

It s a 1999 Ford Crown Victoria and is not an interceptor model. I just changed the oil about 3 weeks ago and haven t even driven 500 miles since I bought it. Toral miles are 249,556. Any advice would be a great help. Thanks!

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