Randy,
I’m a little confused about the location and number of O2 sensors on a 2000 Mustang GT. From what I’ve gathered, there is one sensor in front of the passenger side cat (DY1090) and two sensors behind each cat (DY1039).

Is it correct that the O2 sensor in front of the passenger side cat is the only one the computer uses to adjust the fuel mixture? If so, I would only need to order one DY1090. Would you agree there’s no point in replacing the two O2 sensors after the cats if they aren’t throwing any codes?

Please correct me if I stated anything wrong. If I got lucky and got it all right, how much is one DY1090 O2 sensor? Anything else I need to purchase in order to install an O2 sensor?

 

your car has ONLY 2 Oxygen Sensors, both are located infront of the cats and ONLY they control fuel trims......now, aft of the cats there are 2 Oxgyen Monitors that ONLY monitor catalyst efficiency, so you'll only need the 2 O2 sensors and there $69.00 each, + s&h and always in stock...

 

Ok I see. So there's two that I need to replace. Thanks for the constant support. You'll be getting a call from me soon to order some O2 sensors. Thanks!

 

ok, sounds good by-me