406 Coupe engine damage

Hello My Coupe (BJ2003) died to me this week. Shortly after the start of the car came a message “Environmental protection system engine weak” , then drove about 500m , then there was a bang in the engine room and the beast stood. Let the car to the workshop, get a rental car and the next day tell me that the engine was over. The following explanation was given to me: Supposedly the crankcase ventilation had frozen, the oil would have searched the way over the air filter, so that the he engine oil sucked in -> overpressure -> engine wide. Does that sound plausible? I had already heard that when crankcase ventilation is frozen the oil rod is pushed out or the oil filter is pressed out of its holder with appropriate sourness in the engine compartment, but suck in oil??? Luckily I have at that time ( 3 crosses !!!) the warranty Plus completed, so the PUG for everything (except oil) comes up. Does a heater for the crankcase ventilation bring something? Gruss Th granules