Originally Posted by Volvo Diesel

I doubt that a car with 177,000 miles still has a trap oxidizer. It has probably been replaced with the trap catalyst which, on a W123, is identical to the trap oxidizer, and is supposed to be a lifetime part. As Diseasal suggested, however, it’s probably full of soot and replacing it with a bypass pipe would be a good idea if your state doesn’t have strict emissions inspections for old diesels.

Congratulations on your purchase and I hope you have fun working on the car. I’ve always found this forum to be very helpful and responsive.