Hello members, I was wondering if there's anyone with a diesel engine and OBD2 that is able to look up their exhaust temperatures and share them with me. My engine light came on the other day and I had a code P2457 which relates to the EGR cooler system performance. I then plugged in my OBD2 and of the four exhaust sensors, one to three had readings while sensor number four was reading minus 40° c. My vehicle was brought to a dealer and they said this code came up because the engines computer need an update. Since they have performed this update, number four sensor still reads -40°c. Not sure if a computer update would throw a check engine light so if any members can share any ideas with me that would be most appreciated. Attached is a screenshot of my sensor readings. Thank you.