Yes, the NOX Cell has been a major problem with the ESP/OPUS Gen 3.
The ESP/OPUS Repair Technician in the Fairfield/Vacaville/Suisun City
area has been changing NOX Cells on a daily basis on the New Gen 3.
Along with the "Gas Cap Assembly" for gas cap calibration.
And Yes, sometimes I have had to calibrate two times now and then.