Ideas and suggestions to my X5 issue

[tmv]

I was cruising home with family from NC after the weekend trip. The SAV suddenly downshifted and lost power. I also heard some poping sound underneath. I thought it was transmission related. I pulled over, walked out and check. When I looked under, the cats were glowing red at the rear section. The X5 could barely keep the idle. I shut it off, called a relative to pick us up and a tow truck to get the X5 home.

This is my initial diagnostic: excessive un-burn fuel get burn in the cat. It might have melted the inside and block exhaust flow. No CEL and no symptom before it happend.

Transportador suggests that I also look for blockage or damage after cats section, that would cause exhaust flow constriction.

What do you think?

I'll find out the cause first and fix it before having the cats replaced.