ZeRo MaX

iTrader: (4)

When do I know when to change the 02 sensor.. should i change all 2 or 3.. or how many ever i got.. i think i have 3.. not sure... i have a fed spec...

slizan99

iTrader: (1)

are you getting a code for a bad O2 sensor?

KINGMAX

I think the CEL will come on when you have a bad O2. Also I think there is a seperate code for each one.

WaarrEagle

iTrader: (1)

I changed mine when the CEL came on and told me to change the front heated O2 sensor. I wouldn't worry about them unless you are getting the code or terrible gas mileage.

indigomax

yes terrible gas mileage...i check my codes last week and nothing...i had like 250 miles per tank. I check the Sensor(haynes manual instructions)and i saw a little high resistence on it...both( bank R and L) so i took to my friend nissan dealer...to check with the computer tester...and we saw that the Volt. of the 2 sensor was a little but(haynes manual says it should be from 0.1 to 0.9 v) and it gave as 0.01 or 1.18, some times the V didnt change with high rpms............so Guys if you dont have any codes?? but you have bad mileage...just checked cause is simply...the sensor can work and will not give you any sing of bad.........but sometimes the V and Resistence would be bad for the car years...and miles so i recommend to change it every 50,000 miles.

Dave B

About the only time an O2 sensor will throw a code is when it's pretty much dead. It is very possible for an old O2 sensor to be slow to react while the ECU figures everything is okay. Usually it's the front two O2 sensors that go bad (one in each downpipe of the your y-pipe). A slow reacting O2 sensor can cause bumpy acceleration and poor gas mileage. Most O2 sensor producing companies recommend replacement at 50K miles which is probably a bit early. I've read that 100K is around the time to start looking for OEM replacements.


Dave

I30tMikeD

iTrader: (8)

I was lead to believe a bad o2 sensor, the left front htd in my case, would cause bad gas mileage. While my CEL was one for the o2 sensor I made a trip from Chicago to Oklahoma and got 26mpg. I replaced it while I was there and on the drive back I got 26mpg.
So maybe a bad o2 sensor won't effect gas mileage? Or maybe highway driving is different?

maxNYC

iTrader: (1)

check engine light notified me that mine were going bad. i had two replaced on two separate occasions.

indigomax

the 02 sensor will effect the gas mileage..of course you will notice more on city trips, cause the ecu should work more about trying to make the engine run ok....under rich and lean changes....if you drive on highway your speed will be almost the same......so the ecu with the 02 sensors will not work a lot like city stops, etc.
Right now after change my 2 02 sensors my gas mileage wowww went to normal on city(21 mpg) man!!! the gas here is a s...t so 21 mpg is a miracle.