2009 Vauxhall Other Insignia DPF

Hello There, I have a problem with my Vauxhall Insignia 2.0 CDTI 2009. After DPF was removed still Warning message Coming Back '' Service vehicle soon '' it doesn't go in Limp mode but when I plug it in to the code reader it shows P2458 fault code . To be cleared first I have to reset Exhaust temperature sensor and then clear an error .This error appears only when I go for a long trip ! What can cost this problem ? Can you help me please !?
I am looking forward for your replay !
Atanas