68rfe limp mode issue
 

I have searched the forums for the last month for an answer to this and have had no clear answer .
I've been having an issue since I bought my truck, it is an 07.5 3500 4wd with 68rfe trans ...
Codes are: P0875 Dodge - Trans Fluid Press Sens/Switch C Circ
P0489 egr control circuit
Now I do have a sinister diesel EGR delete with EFI live auto CAL programming to override any DTC issues dealing with EGR and DPF deletes... So?

Basically when the trans temp is NOT at operating temperature IT WILL SHIFT DOWN INTO THE FOURTH GEAR A.K.A. LIMP MODE 1-3 TIMES UNTIL OPERATING TEMPERATURE IS NORMAL.... When it does, it goes into limp it will launch in 1st and then shift directly to 4th, Each time if I shut the truck off and turn it back on it will shift normally.

Has anyone ever had this problem? I've read about replacement of the valve body, also the servo located on the side of the transmission. If anyone can give me any guidance I would really be thankful

There has been a code correction made above. Any info is truly appreciated! Thanks in advance.