i recently installed the invidia 70mm test pipe and v3 exhaust and it worked fine, i drove for a whole day without the cel turning on. but after i installed a j racing snokel and k&n drop in all of a sudden boom, don't know what it is, didn't invidia release the test pipe with a cel fix? any help would be appreciated, thanks o and the cel code is p0420

 

Get the DTC 1st.

 

at the risk of sounding like a noobie, "DTC" ?

 

Diagnostic Trouble Code.

 

o, i forgot to post that, it was p0420