memoniz

I have an emission issue with my truck. It's a '96 w/300 auto. In NC, you can get an inspection waiver if you have spent at least $200 on trying to fix a problem and its not a safety issue. I get a p0411 code when I take it to have read. I have tried to find the problem, but not wanted to go to the more expensive fixes. So I have bought $200 worth of random emission parts to replace since the truck has 281,000 miles on it, figuring any new part could only help. The downstream O2 sensors wire seems to run up and over the transmission ( I couldn't see the connection point ). Is this something I have to drop the tranny for or is there a way to disconnect and connect the new sensor without moving anything? I have never tried to change it before so don't know really whats involved. Thanks.