A few days ago I replaced my rear O2 sensors, now last night pulling out of a store, I hit a bump and both these codes popped up. They say Catalyst Efficiency System Below Threshold...at this point I'm really fed up with my car, lol...I keep having to fix stuff...but anyway...

I am running test pipes but I've never had a problem before this.

 

I have the same exact problem! please help

 

Are you running the oil non foulers. If not get some. Reset the ecu and no more problems.

 

I dont want to sound like an idiot but what is "oil non foulers"?

 

They are more commonly known as spark plug anti foulers, they sell that at any auto parts store.

 

i have some predrilled and ready to go if u wanna buy them. i used them for 1 day, well a few hours.