I have noticed a decrease in fuel economy after I had to change to a new MAF sensor after I did the UIM/LIM job.

I went ahead and did a Plug and wire job first, but the gas mileage still kinda stinks so i want to go ahead and replace the front O2 sensor...it is well over due anyhow..

so my question is which connector do i use? One is square and one is flat. Trying to order this part while at work and thought i could get a quick answer here before i get off work and pop the hood to see which connector i need..here are what the two look like



Both of these parts are listed as "for my car"...I know not to get bosch, but anyone heard good or bad things about "tru-tech", denso, or AC delco?

thanks! by the time i got your reply, i already went and looked..but i appreciate the reply any how..