the car: 1997 XJ6 base, the problem; persistent (4) not ready on OBDII check.
I was reading on an entirely different vehicle forum, of someone having the exact problem, and suggestions coming back that it could be a blown fuse that supplied power for the memory, like for the radio station memory hot that must be working to store pre-sets. Any chance this is the case here? I’ve learned to live with it, the car runs great, & even gets decent fuel mileage, but won’t pass conventional emissions testing. My state allows for low annual mileage (under 5k) cars to be deferred, and I’ve been doing that for several years. However, if there is a fix for this, that would be better. The sensors stay off line, in order of appearance: Catalyst Mon, Evap Sys Mon, Sec Air Mon, Oxygen Sens Mon. It throws no codes, and if you have a reader capable of use while running attached, it shows fairly normal O2 activity on all 4.