The extenders are for the front. I just installed a set of Stainless power 1 7/8" headers and haven't gotten that code using the extenders they provide.
I got a P0420 and a code for voltage low on the bank 1 sensor 2, that turned out to be a exhaust leak, so far i've only gotten the efficiency code on a cold day, other wise i've been through over a tank of gas and only gotten the one efficiency code.
|