The 22psi is minus 14psi atmospheric pressure so you actually have 8psi at idle, the ecu would have flagged it up as to high if it was actually 22psi
I would just drive and put about a 100 miles on it and it should clean itself up, if it doesn’t then get a good code reader and force a regen on the dpf.
I am presuming the reading is same as if it was boost pressure in that atmospheric is taken off ?