I had the front bumper and headlights replaced. Went to pickup the car and fail safe message was displayed on dash. No codes car runs great. Any ideas?

 

 

2000 s-type 4.0 v8

 

It's protecting itself (well, you) from a disaster.

It may not be able to flag codes, depending on how much is wrong - e.g. it needs to know a lot works in order to home in on the real problem.

You may have pending codes. (You will definitely have P1111 or P1000 - which?)

You may have unset OBD monitors - check and if so then each suppresses a lot of codes.

OBD live data might reveal some wacky value - worth looking.

You know the 4.0 can have issues with tensioners & have checked your is OK / replaced them? See existing threads...

 

I had the chains and tensioners changed last spring.