Sorry to resurrect this topic - but in my wife's 335i a rich condition led to the cat exploding. Basically over time unburnt exhaust chunkies went downpipe and settled in the honeycomb. It ignited at some point and sent cat material down system.
Is it possible - open mind everyone - that the cold start warmup is warming up the cats to also prevent rich exhaust from going into the cat and reducing cat life?
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