The warranty has timed out but not on mileage and the problems are getting costly, had the truck into the dealer for “service emission system” flashing on the DIC, and the check engine light on, the code was P2202 nox sensor #1, the dealer changed it out and ran a regen then a reductant fluid test RFQT and it wouldn’t pass, so the tech changed nox sensor #2, did another RFQT and it still didn’t pass, then did a second regen, so now they want to replace the DPF because they say it’s plugged, my question to the tech was, why didn’t the tech2 show that on the first diagnosis, he said he couldn’t because there was no fault code for that, so, I’m thinking they are just pushing parts on me, or are they correct when they say they couldn’t tell the DPF is plugged? The truck ran fine lots of power as usual, 125000km on it 2/3 of that is highway driving, so the regents were happening, as the tech2 showed there was one done about 300km before I took it in, they also changed out the DEF fluid to be sure it wasn’t expired, but I had put 20 litres in before the last trip. I’m not convinced it’s a plugged filter, anyone know what else could be keeping the RFQT from passing?