Doc face plug alarm

[Hendog83]

Hey guys Im new to this forum I have the cm871 cummins and I keep geting the face plug alarm at least twice a week, I had the doc replace in may of 2016 and both filter and doc clean last month along with a erg tune. When cummins clean the filter and tested it they said it check out but it was on its last leg which that's hard to believe with only 270,000 thousand miles on the filter and clean twice. My local shop did a injector test, a smoke test also a force regen and it raise to temp in a good time frame. My fuel mileage is low also in the 5s range any suggestions will be appreciated.