I have a 2003 Jaguar s type v8 and it has code P1254 what does this mean

Question

My Jaguar s type v8 2003 after starting it in the morning it came up with the check engine light
i scanned it with my ELM327 i got code P1254 i cleared it, turned off the engine and restarted it, still check light is on, i scanned it again still code P1254.I try to drive out and its quiet slow it cannot move as usual .What is the problem i wish to get this
fixed
asap.