DTC B1D31-94: Flame Detected Prior to Normal Operation - Unexpected operation: Action

NOTE: The fuel fired booster heater assembly contains many serviceable components. It should NOT be necessary to replace the entire fuel fired booster heater unit to rectify this fault

Check exhaust system and air intake for blockage, kinking or damage
Refer to the appropriate system wiring diagrams and check the fuel fired booster heater glow plug circuit for short circuit to ground, short circuit to power, open circuit, high resistance. Repair the circuit or install a new glow plug located within the fuel fired booster heater as necessary. Using the manufacturer approved diagnostic system, clear the DTCs and perform routine - AHCM Operation Test (0x9013). 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