1997 Jaguar XJ6 engine light stays on

Fixing the light is easy-just pull the bulb.

But, the state doesn't look at the bulb. It uses the diagnostic port to read the computer. The computer will squeal on your actual fault and the technician will tell you it'll cost you a zillion dollars to fix it, because this is a Jaguar. A light that comes back on that quick is usually a serious emissions fault, like a bad EGR or lambda sensors, especially if not coupled with restricted performance (limp home mode).

Call around to your local auto parts stores. Most will read the codes out and tell you what they are for free. Once you have the codes, post them and then we can help you further.