Had been dealing with p2096 for 2 years when i finally had to find a fix so i could pass emissions. Solved that one by replacing the supercharger intake tube gasket which was leaking and spewing oil onto the block. After getting that code by the dealer and reseting the adaptations it looked like I was in the clear. Then the p0240 (cat below efficiency) code popped up randomly and off and back on. I can clear it and it will stay off for a while so i should be able to get through emissions, but I was wondering if this could just be a sign of the second oxygen sensor going bad or will i have to replace the out cat downpipe assembly?

2005 S with ~99,500mi

side note, does anyone live near bowie, md and have a tensioner tool i can borrow

 

Usually that code means an exhaust leak or a defective cat. Get a rubber mallet and hit the cat.. if you hear something bouncing around inside the cat itself is falling apart and is defective