So I've noticed a marked increase in the price between Upstream and Downstream sensors for my 98 Mazda B4000.

I'd love to be able to purchase all four at the $25.00 price on RockAuto, but from past searches on the forum it appears they have different electrical hook ups.

Is this true?


Anyone know of any cheaper place to get Oxygen Sensors? Are the cheaper ones not 'plug and play', sorta speak?


I've got a trip coming up of over 700 miles, I'd like to get as much MPG I can squeeze out of her, 19.5 (east) and 18.5 (west) have been my recent 400 mile trip totals.

 

I know when I got mine there was an option to just splice the old butt on too the new sensor. It knocked a decent amount off the price, but I ended up going OEM anyway. As far as I can remember though, all three of mine had the same type of hook up. If no one else chimes in than I'll go out and look later.

 

?You have 4 oxygen sensors on your truck? :O.

the 'upstream and 'down stream' work together to monitor the catalytic converter and adjust a\f ratio as needed....

 

I just checked, I only see one downstream oxygen sensor, so I assume the source I read about four was incorrect.

That knocks a pretty penny off, and I'll probably just go with OEM then.

 

Only the upstream affect engine efficiency.

If the downstream is bad or senses an inefficient cat, it will set a CEL/code saying so.

Upstreams get lazy over the years and the computer is designed to adapt to that, but fuel mileage will go down as the fuel trims go up as a result.

In short, replace only the upstreams for gas mileage improvement.
Reset the computer by disconnecting the battery and turning on/off the headlights.

Old HEGO sensors (should be replaced every 60,000 miles) from http://fordfuelinjection.com/?p=31

Bosch O2's are good too. Price them locally and at RockAuto.com for reference prices.

 

Thanks,

I re-checked the codes and it is Bank 2 Sensor 1, thus is downstream and doesn't affect gas mileage,performance correct?

 

Bank 2 sensor 1 is driver side upstream so it definitely could affect fuel economy.

 

Thanks Bob.

Now to spend the pennies. :(

 

I busted my knuckles I scraped my arms, I bumped my head, and threw a temper-tantrum, but could not get the driver side, upstream, O2 sensor off, the best I was able to do was unplug it.

I could not get ANY of my tools to fit in the space, I was able to attach the socket to the O2 sensor, just didn't have the space to apply torque. ( I went from under neath, I could not get the fender liners out.)

Looks like I'm going to have to go to the mechanics to get it done.

:(