I need to know this because my gas milage is absolutely rediculous. Should i try cleaning the 02 sensor that's throwing a code before i buy a new one?

 

... it will affect your mileage. I personally have found that cleaning them doesn't always work. You have to replace it anyway, so I would just put the new one in it now.

 

Replace them. They have a big influence on gas mileage, especially since they're throwing codes

-matt

 

O2 sensors in the headers effect the rich/lean mixture of the throttle body. The Ecu controls the mixture using feedback from the O2 sensors. I found if the O2 sensors are old and slow to respond, your city mileage will suck. After the o2 sensors heat up your mileage will be better(hwy).
I say change them every 100k!!

 

Besides the drop in gas mileage, is there any other way to diagnose if an 02 sensor is bad or going bad?

 

CEL

-matt

 

Hook up a good OBDII scanner and monitor O2 sensors.

 

All 3 of my o2 sensors went out around the same time. I know the one in the cat won't do anything for gas milage but I replaced all of them and didn't really notice any significant increase in gas milage. It may have raised it a bit but not enough for me to notice a difference.

 

When replacing the O2, does it matter what brand/model I use?

I have not figured out the brand for the OEM (help anyone?), but know that Bosch are readily available. I imagine that I could get the OEMs at a decent price online.

Would also welcome suggestions on the best/most reasonable place to purchase 02 sensors? If ebay, what seller or store?

Thanks, in advance.

 

I got mine off ebay. A company called walker makes them and they have been working fine for me and seem to be lasting a while. No problems yet. Those were the cheapest price I could find. They were about $70 each shipped for the 2 front and the rear was somewhere around $50-$60 shipped.

http://cgi.ebay.com/ebaymotors/95-99...spagenameZWD1V



http://cgi.ebay.com/ebaymotors/Nissa...spagenameZWD1V

 

I went to Sullivan tire to get an inspection a couple months ago, they had a sign up that said a bad O2 sensor will cost you 88cents a gallon

 

I replaced the 02 sensors in my 2000 maxima 5spd with 104k and now get 28mpg when I used to get about 25.

 

o2 sensors make a ****load of difference. they send the signal to the ecu for how much air/fuel mixture to expel. I say change them if you haven't done so in a long time. the best way to check if you get an increase in mileage is to reset your trip odometer after avery full tank. depending on your driving habits, the final number ranges in give or take 15 miles.

I've bought bosch for my car, the code went away, but my gas mileage is still terrible. Don't go with Bosch. Get Denso.

 

Thanks, all for the ebay referral and the comment about Bosch vs. Denso.

Can someone elaborate on how many O2 sensors there are (I think 3), which ones are most likely to impact gas mileage or performance, and which ones an avg do-it-yourselfer might be able to change on his or her own?

p.s.: Has someone posted instructions/pictures about how to change each of the three O2 sensors?

I got P0159 and P0158 codes, which suggests that I have a problem with the "bank 2, sensor 2" sensors. I would like to fix myself, but am not sure whether it would be relatively easy with basic tools.

Thanks!!!

 

it might be harder with a stock y-pipe because the pre-cats get in the way. Also, with gas prices like this, its much much cheaper to buy any 02 sensor you need to replace rather than waiting for it. But also get the one that directly plus in which is oem style, not the ones where you have to cut your own wire and attach to it with the hold. Sometimes it could be the wire, you just never know.....

 

Bosch makes the OE sensor and they're good for ~100k miles. Bosch, Denso, and NGK all make good O2 sensors. I'd stay away from Walker though. They're cheap an they only last 30-50k miles. I put in universal bosch sensors for $60 each at autozone a couple of weeks ago.

There's 3 O2 sensors in a FED car, one in the cat and 2 in the Y-pipe. The one at the cat doesn't affect gas mileage or performance. To replace the O2 sensors you simply need a socket wrench and a special O2 socket that you can borrow from autozone. If you have an aftermarket y-pipe, all you need is a crescent wrench.

The OEM style with the connector is more expensive, but the universal one in which you splice your own wires is about $30 cheaper and performs just as well.

 

oxygensensors.com they have a variety to choose from, I think it's free shipping too.

 

In a word they probably are one of the biggest influences on your engine performance and gas mileage besides things like the knock sensor, different type problem/ cause, etc. but its really all the same in the end.


..on a different note alot of ppl are under the false impression that you just clean them to make them work better.. WRONG. If theyre going bad its because the sensor solenoid has worn out/down over time.

 

It doesn't affect your WOT performance since that's open loop and the ECU relies only on the MAF to calculate the amount of fuel needed.

In closed loop, it greatly affects gas mileage. If the sensor is bad, it'll run rich and you'll get extra carbon deposits. If it's totally dead it'll run super rich and if you ignore the problem, it'll eventually plug up your cat.

 

I'm starting to get a puttering sound from the exhaust right under the car when i rev the engine. What could that be, a clogged CAT?

 

question.. regarding kock sensor. you mentioned open loop which is a valid argument and fact, okay so with a bad knock sensor would timing return to normal in WOT because of open-loop (does it have anything to do with that)? I was asking only because I'm under the impression that the ECU retards timing all the time once it detects a bad knock sensor. side convo sry but I needed to know this, thanks.