Intake manifold temperature at zero

hello everyone,
I have tech tool and try to do forced regen. Getting message:
"Idle the engine until the intake manifold temperature is above (0) and try again"

Background, have replaced inlet nox same day, outlet nox replaced 4 months prior, soot level gaug we is pretty high and seems to stay that way, i hope - I have 2k miles ahead.
Today I replaced temperature sensor at the charge air/turbo area and still same.
Boost sensor new 5 months ago
Please help