Home >> Land Rover >> 2017 >> Range Rover Sport HSE Dynamic >> Repair and Diagnosis >> Quick Lookups >> DTC Index >> Diagnostic Trouble Code Index DTC: Telematics Control Module (TCU) -- Range Rover Sport/L494 >> Diagnostic Trouble Code Index DTC: Telematics Control Module (TCU) >> Description And Operation >> DTC U2109-91: Back-up Battery - Parametric >> Possible Causes