traction control light flashing

[chrisq64]

hi I have searched the interweb  but no luck my 2001 3ltr auto had the abs light /dsc/and traction control lights on so I read the codes and as suspected it was a rear sensor .fitted new sensor all lights fine except traction control light still flashes all the time .if you push the switch read out on dash shows dsc on /off. back to code reader reset all fine for a while . then it starts flashing again. tried neg battery terminal to poss as suggested some where but still flashing . code reader gives code u1243 .scp  (j1850) invalid or missing data exterior environment. so any more ideas or is it off to jags for a reset

cheers chris