After having a new Catalytic Converter installed by Volvo our engine sound deepened. Acting on the advice from another Volvo forum I took our 2000 S70 GLT SE w/2.4 Turbo 2WD to a local exhaust shop for a check of the exhaust bolts. Immediately upon raising the car the shop owner told me that my new Catalytic Converter was red hot and about 2 feet of the exhaust pipe connected to the rear of the Cat Converter was also red hot. Current mileage is approximately 96k.

No warning lights are illuminated and the car is running just fine. Gas mileage is very good at about 20.4 miles per gallon.

 

Red glowing Cat means Lean running condition.

I would check for Vaccum leaks and try to have the codes red.

It might not have triggered teh light yet but might have codes present.

A big vaccum leak could make it run lean.