DTC B1D23-85: Overheat Sensor - Signal above allowable range: Action

NOTE: To check the operation of the fuel fired booster heater, perform routine - Auxiliary Heater (AHCM) Activation Test (0x900A). Repeat the routine if excessive smoke is emitted from the fuel fired booster heater exhaust.

Using the Jaguar Land Rover Approved Diagnostic Equipment, clear the DTCs and retest. If the fault persists, install a new fuel fired booster heater as necessary