Q: 1999 Jaguar xj8 is on safe mode and doesn't start

This particular sequence, "stability control fail and engine safemode" has been previously reported and in some instances has been traced to a defective throttle body, ABS module and/or brake light switch. However, those are just some of the possibilities. Initially, a mechanic would use a code scanner to see if any trouble codes have been stored. If there are no stored codes, the mechanic would use a standard no start diagnostic. If you request the no start diagnostic the responding certified mechanic will get this taken care of for you (the initial list of possibilities listed at the outset of my answer would be examined first). If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.