Hello chaps! My Disco rolled over 90K last week and I've noticed a slight drop in MPG. And with the way gas prices have been, I think it is about time!

Has anyone ever bought and used these specific O2 sensors on Amazon: Amazon.com: Bosch 15175 Oxygen Sensor, OE Type Fitment: Automotive

and: Amazon.com: Bosch 15630 Oxygen Sensor, OE Type Fitment: Automotive

Also, if I remember correctly (it was a couple of years ago), I think both Spike & Mike said that the ones before the cat are the most important and that the downstream sensors really don't do much? Anyone's thoughts please...

Thanks!

 

I bought my O2's off of Amazon.
And yes, only the fronts control engine fueling, the rears are for emissions only.

 

The Bosch are quality O2's. I replaced all 4 of mine and a 5th because I didn't get one of the cables tie wrapped good enough. The drive shaft ate through it in about 2 weeks. So be sure to not leave any slack hanging where it can rub against anything or you will be replacing again.

 

Thank you gentlemen!