One problem related to catalytic convertor has been reported for the 1999 Volvo V70. The most recently reported issues are listed below.
This car has had a sulfur smell in the emissions since the day of purchase. When it didn't go away at 200 miles, complained to the dealer. They said it would take 2000 miles. Didn't go away by them. They have replaced the O2 sensor, downloaded and upgraded computer, replaced the mass air flow sensor and we are on our third cat converter but the car still smells of sulfur. Especially noxious at low speeds, stop and go traffic and idleing! in June of 2000 they said they weren't authorizing any more repairs on the car. But the car still smells. Concerned about the smell being an irritant to my son who has history of asthma.