nedriver

Thanks to everyone for your help! I think I'll replace the sensors first.....

Hi all, I have a 2002 Outback with the 2.5, and 126Kmiles. The check engine light came on while I was on a trip so I visited the local dealer. They told me that the "catalyst efficiancy below threshold" code was activated. I was also told that this means the converter(s) are failing. $900-$1500 ouch.... The car also accelerates poorly, and sometimes does the "shake and shimmy" for a brief time. Air filter, coil, fuel filter, plugs, and wires all new. Questions: - 1. does "failing" mean plugged or not working correctly? 2. Does anyone know aftermarket converters? 3. Will I also need to replace sensors, etc? Thanks!