2021 ENTEGRA CORNERSTONE Engine Problems

I HAVE OWNED BOTH A 2019 AND THE NEW 2021 ENTEGRA CORNERSTONE MOTOR HOMES. ON BOTH MOTOR HOMES, THE DIESEL EXHAUST FLUID (DEF) SENSOR HAVE FAILED IN LESS THAT 2,000 MILES. WHEN DEF SENSORS FAIL THE ENGINE CAN GO INTO DERATE WHICH IS 5 MPH IN LESS THAT A COUPLE HUNDRED MILES. THIS PROBLEM IS LEAVING MANY LARGE DIESEL ENGINE OWNED VEHICLES STRANDED, FROM MOTOR HOMES TO LARGE OVER THE ROAD TRUCKS. I HAVE CONTACTED SPARTAN MOTORS THE MANUFACTURE OF THE CHASSIS, WHICH REFERRED ME TO SHAW DEVELOPMENT, THE MANUFACTURE OF THE DEF SENSOR. SHAW DEVELOPMENT REFUSES TO TAKE CALLS OR EMAILS REQUESTING INFORMATION REGARDING THIS PROBLEM. THE DEF SENSORS WAS A REGULATION PASSED BY EPA IN 2016, STATING THE DEF CONCENTRATION BE MEASURED IN THE DEF TANKS OF VEHICLES. HOWEVER THE DEF SENSOR MANUFACTURES CANNOT SEEMS TO MANUFACTURE A PART THAT WILL WORK AND NOT PUT ENGINE INTO DERATE....