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how do i know which o2 sensor is bad?

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JiveMasterT

15+ Year Contributor
1,849
7
Jan 3, 2004
Chest of Westerson, New_York
i have a check engine light for a bad o2 sensor and i dont know which one it is. can anyone tell me what the different things mean when you get the check engine light? i know it gives a designation as to which o2 sensor is bad but i dont understand it and i dont have it in front of me atm. anyone give me any advice?
 
It should tell you if its bank 1 (upstream in the o2 housing) or bank 2 (behind the cat). Chances are its the one in the o2 housing...thats the one thats subject to the most punishment.
 
oh boy. how difficult is it to change the one in the o2 housing? i know there is a vfaq for the one behind the cat (which i dont have) but i didnt see anything for the one in the o2 housing.
 
JiveMasterT said:
oh boy. how difficult is it to change the one in the o2 housing? i know there is a vfaq for the one behind the cat (which i dont have) but i didnt see anything for the one in the o2 housing.


Bloody easy. Get an O2 socket, unplug the O2 sensor, get underneath the car and take old one out, put new one ine, plug new one back in. Done.
 
CyberEye said:
Bloody easy. Get an O2 socket, unplug the O2 sensor, get underneath the car and take old one out, put new one ine, plug new one back in. Done.
so i should just figure out which one it is, get one from like oxygensensors.com and be on my way? thanks!
 
JiveMasterT said:
so i should just figure out which one it is, get one from like oxygensensors.com and be on my way? thanks!


it's more than likely your front one. The rear one basically just tells the car that your cat is still present. So unless it's clogged it probably isn't that one. But check the engine code first just to be sure
 
CyberEye said:
Bloody easy. Get an O2 socket, unplug the O2 sensor, get underneath the car and take old one out, put new one ine, plug new one back in. Done.

Depends on how easy it wants to come out. I got mine red hot and it still wouldn't budge. I ended up just getting a new o2 housing. I'm sure it could have been able to come out after alot of coaxing, but I didn't want the hassle.

But other than that it is relatively simple. Make sure to get one that has the harness that plugs right into your main harness...I've seen splices come apart with the heat in that area.
 
blackGSX2g said:
Depends on how easy it wants to come out. I got mine red hot and it still wouldn't budge. I ended up just getting a new o2 housing. I'm sure it could have been able to come out after alot of coaxing, but I didn't want the hassle.

But other than that it is relatively simple. Make sure to get one that has the harness that plugs right into your main harness...I've seen splices come apart with the heat in that area.

ok, so its O2 sensor (1) in Bank 1. I'm assuming that means the front one. Lovely. And its not even the O2 sensor that is bad, its the heater for it, according to my logger. Oh well, i guess ill have to get a wrench on it and wrestle it outta there.

Btw, where do you guys get your o2 sensors from?
 
JiveMasterT said:
ok, so its O2 sensor (1) in Bank 1. I'm assuming that means the front one. Lovely. And its not even the O2 sensor that is bad, its the heater for it, according to my logger. Oh well, i guess ill have to get a wrench on it and wrestle it outta there.

Btw, where do you guys get your o2 sensors from?


Do yourself a favor and get an O2 socket, or the appropriate sized crows foot socket. You'll have a tough time getting a regular wrench or socket on there.

Check out www.sparkplugs.com the Denso lead safe sensor is great
http://www.sparkplugs.com/more_info.asp?AAIA=1205884&pid=1937

or just go to your mitsu dealer, or Napa or something.
 
blackGSX2g said:
Depends on how easy it wants to come out. I got mine red hot and it still wouldn't budge. I ended up just getting a new o2 housing. I'm sure it could have been able to come out after alot of coaxing, but I didn't want the hassle.

But other than that it is relatively simple. Make sure to get one that has the harness that plugs right into your main harness...I've seen splices come apart with the heat in that area.


Umm if you got your O2 sensor red hot, that would explain why you couldn't get it out, you expanded the sensor in the hole when you heated it. You should have heated the O2 housing around the sensor, and not the sensor.
 
CyberEye said:
Umm if you got your O2 sensor red hot, that would explain why you couldn't get it out, you expanded the sensor in the hole when you heated it. You should have heated the O2 housing around the sensor, and not the sensor.

I meant the threads around the sensor...the o2 housing itself. If I had gotten my sensor red hot I would have melted the wires coming out of it. I sprayed PB Blaster on the threads and let it sit over night and still had no success, so I put heat on it.
 
blah, when i told my mom i needed to replace the o2 sensor, this is what happened...

"when are you going to do this?! its going to be 20 degrees out all next week! just have mitsu do it!" "mom, they want $350 to do it, including the part." "i'll split it with you." "i still have to pay more then." "fine, ill pay all the labor, you pay for the part."

so i think im still gonna order it and try to do it. if it wont come out, then my mom, who is slowly beginning to hate my car, will pay satan to do it.
 
JiveMasterT said:
blah, when i told my mom i needed to replace the o2 sensor, this is what happened...

"when are you going to do this?! its going to be 20 degrees out all next week! just have mitsu do it!" "mom, they want $350 to do it, including the part." "i'll split it with you." "i still have to pay more then." "fine, ill pay all the labor, you pay for the part."

so i think im still gonna order it and try to do it. if it wont come out, then my mom, who is slowly beginning to hate my car, will pay satan to do it.

You could order the part and try to put it in yourself and if that doesn't work, any fairly competent shop should be able to plug it in for you. The job is only an hour of labor, so if you buy your own part and bring it in they will only charge like 50-60 bucks. There is a shop around here on campus that has half off labor for students...its like $45 an hour.
 
UnderPrssureDSM said:
If you have a PocketLOGGER or some other code reader, that might be helpful.

:laugh: Your sig pic rocks!!

Anyway, definitely invest in a O2 sensor tool and a cheater bar. Mine came out pretty easily but some of them can be a definite pain.
 
UnderPrssureDSM said:
If you have a PocketLOGGER or some other code reader, that might be helpful.

yeah dude, i got a pocket logger. its the o2 sensor in the front... sensor 1, bank 1. im gonna try to get the thing inspected, and hopefully it wont throw the cel while its getting tested. (ill just clear the cel before i get tested) im just gonna order it and try to do it myself... if it wont come out ill throw a pipe on the wrench like i do with everything else that wont come out... and if i still cant get it to come out then ill take it to satan.

think i should drive the car to heat things up before i try to pull it out?
 
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