Join Date: May 2010
Ferrari Life Posts: 3,338
There are a few threads over on that "other" site, including pictures of cats glowing red. However, there doesn't seem to be consensus on whether that is "normal" or not.
As an engineer, I will hazard a guess: Most metals will begin to glow red about 800 degrees F. By 900 degrees or so, glowing cats would be visible in daylight. So, depending on how close the cats are to the exhaust ports, I think it is reasonable to expect they could get red hot. This is why some manufactures have placed ceramic coatings on their exhaust manifolds (Jaguars come to mind). This reduces the radiated heat in the engine compartment.
So, as Boxer states, I think if they were "too" hot, the CEL would illuminate.