My truck still has 3 of 4 original O2 sensors. I had to change the right rear sensor at 220,000 because the internal heater had failed and caused a code. I will not change any of the others untill they fail. From what I have read, 02's are good or bad. They will tend to get a little slower to react with age/mileage but it is not enough of an issue to cause any problems or poor mileage. The computer uses the rear 02's to adjust the long term fuel trim. They are not just for monitoring the cats. Cars will still run fine with the rear 02 cheated with a resitor, but why unless you need to remove the cats to run leaded race gas. I have also seen problems where cars with heated 02's where the internal heater shorts out and shorts out the computer. This causes the car to die and not restart until thing cool. If you have a car with a heated 02/02's and it dies and will not restart right away, change the 02's.

If you guys want to throw out good 02's with only 30,000 miles, ship them my way. They are easy to change and there is no way I'm spending $250 on something that will not have long term benifits.

 

good god man, where are you buying your O2 sensors for $250 at?

If thats what I were being charged, perhaps I too would have a differant opinion. These things are very easy to replace and can easily be found for less then $20 each

 

I have 73k miles, I might as well go and change them and the fuel filter.

 

Petrol,

Where are you getting them for $20.00? That seems like an excellent price. Ford has a list price of $90.00+ and wholesale is around $55.00. What brand are the ones you are using. I think the $250.00 that Bent6 was referring to was maybe the total cost for all four.

 

I bought the downstream O2 at the Ford dealer. I pay wholesale, and it still cost $65. As I recall, the upstream are about the same. Even at wholesale 4*65= $260 + Tax. Retail should be about 25% more. If you are only changing the front 2 you are looking at roughly $175 from the dealer.

Petrol, have you ever bought a 02 for your truck? I'd be really suprised if you can get one for $20. Three wire (heated) 02's cost more. You can get a 1 wire for approx $20. I found this 3-wire on JC Whitney's site.
http://www.jcwhitney.com/item.jhtml?ITEMID=3864&BQ=jcw2

It is selling for $54.

 

Yeah, I too would like to know where you can get a heated 4 wire O2 for $20. Even if it's a cheapie that's still a great price. Best I can do is $49.99 but that's for a Bosch O2, which is supposed to be one of the best out there.

I would say the $250 is for all four.

I would hate to be that guy in Africa, good god $550 each. You gotta be kidding, how much is a big item like a starter or alternator.

 

Good grief - replace them every 30,000 miles? If that was required, you would see it in the maintinence schedule. I've had exactly one oxygen sensor ever fail on any of my vehicles, and I don't make a habit of replacing parts that don't need it, unless a maintinence schedule calls for it. If you are into ultimate performance, then fine, otherwise my vehicles still get the fuel mileage they've always ahd. My '97 has 152,000 on the odometer now, and still gets over 20 mpg reularly.