put a highflow on my car lastnight, o2 censor was reconnected....was driving it today and when i tacked it out it all the sudden bogged out and it said "Eng PWR Reduce"....i was like whatt the f***. Anyone maybe could help me out? tell me why this maybe came on...

 

you wont get that from a high flow, thats omething else, unless u plug the o2 in the wrong slot, as in back in front and front in back, idk, check into how u plugg'd them in, but i havent had a CEL and i complete cut off the second o2,i have a CEL but no eng pwr reduced...you might wanna check everything out again

 

i only replaced the cat, and i plugged the o2 censor back in. i also have a CEL.....im just wondering why that other message came on....maybe too much flow and the computer is'nt used to it. idk

 

Usually that light only comes on when the throttle body sensor is loose. There are a few other exceptions though.