I have a98 TA Stock A4 Gutted converts rear o2 sims 125 shot Last week I was driving home from work so I deceded to play alittle when I floored it my car backfired and codes PO131 and PO151 popped up Ichanged both front o2 sensor and codes come right back as soon as I floor it what could it be Ive changed them 2 times this weeked

 

Check all your O2 sim connections and check the sims themselves for a short to ground. You've probably blown your "ENG SEN" 20A fuse in the underhood fuse panel.

 

Cleaned Mass Air and TB codes want away