Home >> Jaguar >> 2017 >> XJR L >> 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