It has been some time since I asked a question. I just replaced the pipes and the cat on our oldest running Volvo 740 GLE 1988. I also replaced the air hose from the Air Mass to the T. body at the same time. A few days later the cat is burning up. I got the idea that maybe the oxygen sensor is bad and the ECU is calling for gas, which is destroying the Cat ? I then have to ask about the placement of the sensor in the down pipe and route of the wiring. I don't remember seeing it as I replaced the pipes. Question: Sensor in Down Pipe ? Wiring goes to ECU follows what path ? Ideas about the cat burning up ?

turbodog #3 Nine Volvos: 2006 V70 R Manual, 2004 V70 R Auto, 1993 945 T, 1988 745 T, 1988 740 GLE, and the rest all 745 T wagons (not running) one with 302.