A combustion chamber assembly unit for a fuel-operated vehicle heater is provided. The combustion chamber assembly includes a combustion chamber housing (12) with a combustion chamber (18), which is defined by a circumferential wall (14) and by a bottom area (16). An oxidation catalytic converter device (54), through which combustion waste gases can flow, is provided downstream in relation to the combustion chamber (18). The combustion chamber assembly further includes a hydrocarbon storage device (74) or/and a nitrogen storage device (76).