What does the check engine light on mean on a 1997 land rover?

There are pages and pages of theings that can turn the check engine ligth on, you need to have it checked for codes. Another way to look at it, there is only ONE reason for the check engine light to come on, that being, the computer has detected a problem. You don't NECESSARILY need to HAVE it checked, since you can do that yourself. Go to just about any auto parts retailer where you can borrow, rent our buy an engine code scanner. Some of the more helpful places will even help you plug it in and decide what it means if they aren't terribly busy, and if you can drive the vehicle to their parking lot. But in general, you'll need to use a code scanner to find out why the computer has turned on the light. It's just the computer's way of saying, "HEY! YOU... BEHIND THE WHEEL THERE! PAY ATTENTION TO ME!"