Home › Land Rover › 2021 › Defender 110 › Repair and Diagnosis › General Information › Specifications Index › Diagnostic Trouble Code Index DTC: TELEMATIC Control Unit Module (TCU) -- Defender/L663 › Diagnostic Trouble Code Index - DTC: TELEMATIC Control Unit Module (TCU) (G2400918) › Description And Operation › TELEMATIC Control Unit Module (TCU) › DTC B1A01-13: Speaker #1 - Circuit open › Possible Causes