DTC B12B9-64: Auxiliary Heater Control Module - Signal plausibility failure: Action

NOTE: Consider whether environmental conditions may have caused this DTC to log before condemning the unit

Using JLR approved diagnostic equipment, clear the DTCs and perform routine - Auxiliary Heater (AHCM) Activation Test (0x900A). This will operate the fuel fired booster heater for 15 minutes. Note that the routine should be started only when the engine is cool. The routine should be performed with the engine running and with the climate controls set to maximum heat and maximum fan. Repeat the routine again if smoke continues to be visible from the fuel fired booster heater exhaust pipe or from the area surrounding the fuel fired booster heater
If the fault persists, install a new fuel fired booster heater control module located within the fuel fired booster heater, clear the DTCs and perform routine - Auxiliary Heater (AHCM) Activation Test (0x900A)