as i posted earlier, my check engine light came on about 9 days ago, i took it to dealer and for $115.00 they told me it was not the O2 sensors, but wanted another $450 to further diagnosis the problem. I took the car home instead. the fault code was 443 - cat. converter. over the next 7 days the check engine light came on each day while driving home from work - codes 436 - rear O2 sensor problem, plus one 435 - front O2 sensor. well today while driving my wife back from taking her lincoln to the lincoln dealer, my catalytic converter FELL DOWN and dragged on the pavement. when i took it back to the Volvo dealer, they were able to daignosis my check light problem as a crack in the converter. they did not charge the normal diagnostic fee and will repair the problem for $1050 us dollars. as i mentioned earlier, i thought my muffler seemed a little louder, something i had told the dealer - but they ignored.