Home >> Land Rover >> 2022 >> Defender 90 >> Repair and Diagnosis >> Quick Lookups >> Common Specs & Procedures >> Diagnostic Trouble Code Index DTC: HVAC Control Module (HVAC) -- Defender/L663 >> Diagnostic Trouble Code Index - DTC: HVAC Control Module (HVAC) (G2400894) >> Description And Operation >> HVAC Control Module (HVAC) >> DTC B1DC9-13: Cabin Heater Water Pump Relay Control - Circuit open >> Possible Causes