Oxygen sensor location?

Discussion in '8G Lancer - General Information' started by C-lo, Oct 22, 2011.

  1. C-lo

    C-lo Well-Known Member

    Ok so i'm trying to put on my new Injen cat-back exhaust, and the whole exhaust has 3 holes for 3 o2 sensors. Problem is when i get under the car i only see 2, one after the primary Cat Converter, and the the other on further back. Now apparently the 2009 lancers are supposed to have 3 sensors. One in the primary cat and the other ones following. However, i can't find the one that's supposed dto be in the primary cat. Does anyone know if maybe the o2 sensor is position in a way so you can't see it or anyhting like that?? because i got under the car and i didn't see any o2 sensor on the primary cat. Maybe i'm not seeing something, has anyone actually seen all 3 of their o2 sensors on their lancer? (just fyi i don't know if it applies to all lancer trims and models but mine is a 2009 mitsubishi lancer es sport 2.0) also any tips on how to get the primary cat unbolted? because there is no space to work with under there and i can't fit a big enough wrench or ratchet to give me leverage to take out the primary cat bolts. I'm thinking about using an impact gun. Anyway please if anyone know where EXACTLY the first o2 sensor is let me know. the other o2 sensors are easy to see and take out, i'm just having trouble fiding the first one. please help!!!!
  2. 1slowlance

    1slowlance Well-Known Member

    The first sensor might be on the header somewhere. The "primary" cat might be built-in to the lower part of the header. See if you can check around the bottom portion of your header. As for the bolts, They'll probably be pretty tight from the factory to begin with if it's never been tampered with. Seeing as how you're up north, hopefully you don't have any rust. My car came from Ohio originally, I think, and the whole exhaust system was rusted to all hell.
  3. Jogenmaru

    Jogenmaru Well-Known Member

    It might be hidden. Look for any wires going to your exhaust header. Odds are it leads to the 1st O2 sensor.

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  4. SoulEater13

    SoulEater13 Well-Known Member

    i have an ES, the first is in the exhaust header, you can see it from your engine bay. two is in the middle of the cats and the third behind cat 2. i cant remember precissely the last 2 but i know for a fact on mine the number 1 is on the header in the engine bay. im great at turning wrenches seeing that what i do for the navy for the past 6 years. i will take a look at my cat and i will give you the best advice possible. give me a few days to research this, as my schedule is really busy.
    Last edited: Oct 23, 2011
  5. C-lo

    C-lo Well-Known Member

    thanks man i apreciate it.
  6. jdmSTIG

    jdmSTIG Guest

    Three O2s's:
    1. not in use
    2. Is the hO2s, located on the high flow cat on the SES INJEN full exhaust
    3. Near the resinator

    Use a 14mm socket with extensions to reach the spring/ swivel bolts. EASY bro.
  7. SoulEater13

    SoulEater13 Well-Known Member

    ok, use a ratchet and then get the longest combination wrench you have and put the ratchets hand through the closed end combination wrench and use it as a cheater bar. it gives you more leverage. it never fails, i use that method alot on jet engines.
  8. C-lo

    C-lo Well-Known Member

    thanks to everyone, i got the exhaust on and plugged the o2 sensor hole in the down pipe int he injen exhaust. Put the whole exhaust on the car and now running with awesomeness hehehe :p
    thanks to everyone again, check out my progress report when you get a chance
  9. oSHINSAo

    oSHINSAo New Member

    Hello Guys, Sorry to bother, I have a Lancer 2009 with P0420 code, which comes to be the Upstream Sensor, and i have a doubt here, is the upstream sensor near the Engine? or is it the first before the catalyst? is there a way you can help me with a photo here??