NHTSA Complaint #11426798 — 2018 TIFFIN ALLEGRO

RV Diesel Exhaust Fuel (DEF Head) Sensor failure. These failure rendered our RV drivability limited and us stranded at Cummins dealerships, once in 2019 and again in 2020. We have been full time RV'ers and rely on motorhome getting us from place to place. We were lucky to not have the engine derate while driving, but had to pull over on the freeway, there were no off ramps or rest stops for miles as multiple warning lights and codes flashed on the dash so we could call Tiffin to ask for help, what to do and where to go. We where able to get to a Cummins dealer to have it fixed. We were warned to drive slow and straight to the Cummins dealership before the engine derated. RV Diesel Exhaust Fuel Sensor failures have been occurring & re-occurring at an astronomical rate across the country, we firmly believe that RV's should be exempt from requiring DEF / DEF Sensors, period. Please do not wait until there is a FATALITY, OR POSSIBLE GREATER FATALITIES before making this change retroactive for all RV's nationally. The Cummins dealerships and Tiffin have the repair records. The error codes we received was SPM 3521 FMI 11 error code. Looking it up it is "After treatment 1 Diesel Exhaust Fluid Property". Also SPN 3364-9, ECM 1761-9, ECM 3031-9, SPN 3364-9 and ECM 3031-9 showed up.