Home >> Land Rover >> 2017 >> Discovery SE >> Repair and Diagnosis >> Quick Lookups >> DTC Index >> Diagnostic Trouble Code Index DTC: HVAC Control Module (HVAC) -- Discovery/L462 >> Diagnostic Trouble Code Index DTC: HVAC Control Module (HVAC) >> Description And Operation >> DTC B12B9-87: Auxiliary Heater Control Module - Missing message >> Possible Causes