Home › Jaguar › 2014 › XJR Base › Repair and Diagnosis › Quick Lookups › DTC Index › Diagnostic Trouble Code (DTC) Index DTC: Adaptive Speed Control Module (ASCM) -- XJ/X351 › DIAGNOSTIC TROUBLE CODE (DTC) INDEX DTC: Adaptive Speed Control Module (ASCM) › Description And Operation › Adaptive Speed Control Module (ASCM) › U0401-81 Invalid Data Received From ECM/PCM A - Invalid serial data received › Possible Causes