O2 sensors?

Discussion in '4X4 Truck Talk and Repairs' started by bootshowl, Jul 7, 2008.

  1. bootshowl

    bootshowl New Member

    Messages:
    2,288
    State:
    Indiana, J
    My F150 check engine soon light came on, so had it "plugged into", and they said I needed a new sensor. This was about a month after I put new plugs in it. Then I had em reset it for me after replacing the sensor they said was needed. Week later, light comes back on, and they say I need a new sensor on the other bank.....is this common for em to wear out that close together? I'm wondering if there was some confusion as to which bank sensor was bad. Darn things are $50 apiece....Ouh! This was an auto parts place, not a garage, and I just put the new one in they told me. It's not a hard job, but costly, and just wondered how common this is.
    Thanks for any info.
     
  2. drpepper

    drpepper New Member

    Messages:
    6,133
    State:
    Indiana
    What year is your truck and what engine? any large/small exhaust leaks- where?(tell me)
    what was the code?
    give me this info I'll get you on you way to repair instead of guess work... I have a feeling your having autozone or some place like that pull codes for you.
    Bill
     

  3. bootshowl

    bootshowl New Member

    Messages:
    2,288
    State:
    Indiana, J
    Thanks Bill. Yup Autozone, S1B1, then S1B2....or least that's what they said. Won't let you get close enough to see. It's a 99 with the 4.2 liter six cylinder. Auto, air, and 2X. Plain truck. Just rolled over 70K miles. When I replaced the plugs, found one boken on the passenger side, first on the front. (would that be #1?) And when I pulled the sensor it looked dirty instead of burned clean. So it made sense to me with a bad plug, I'd lose the sensor too. But then week later, other sensor code came on. If you listen to the parts guys, that's what happens. Just wondered if it's true.
    I've since read that if we all wanted to reduce emissions and save gas, the sensors are the main vein, LOL. So guess it's just a good idea to replace em. But the 4 wire units have a reputation for hanging in 90-100k, and I only got 70k. But then I had the failed plug too. Appreciate your feedback.
     
  4. jason454ci

    jason454ci Active Member

    Messages:
    1,307
    State:
    Zanesville, Ohi
    First thing I would do is take it to a locally shop and have them check the codes. The guys at the parts stores like to believe that they are mechanics but if they were they wouldn't be working at the parts store. lol. Just because you have an o2 sensor code doesn't always mean that the sensor is bad. A vacuum leak can set the same code. Just remember the parts store is there to sell parts and their $100 code scanner isn't a fix all by no means. If it was us real mechanics wouldn't be buying $5000+ scanners.
     
  5. drpepper

    drpepper New Member

    Messages:
    6,133
    State:
    Indiana
    Okay, thats not the trouble code, thats just telling me which sensor it is... S1 is the 1st sensor from the exhaust manifold on bank 1.
    "S1B2" is S1 is the 1st sensor from the exhaust manifold on bank 2. so your problems are on both banks (left and right side)
    fyi you have 4 o2 sensors, the other two are aft the converter. 2 upstream (s1 bank 1 and 2) and 2 downstream (s2 bank 1 and 2)
    On the right hand (Passenger) side of your engine is bank 1 and contain cylinders 1, 2, and 3.
    left side (drivers) is bank 2 and cylinders 4 ,5 and 6.
    hmmm, the HO2S sensors ("H" stand for heated)senses oxygen content in the exhaust flow and outputs a voltage between 0 and 1 volt.... lean of stoichiometric (the air/fuel ratio of aprox 14.7:1 for gas engines) the HO2S sensors will generate between .45 and 1 volt. btw, having even a very small exhaust leak before the sensor will effect the stoichiometric and cause a code... thats why I asked about an exhaust leak which is one of the common problems and was easy to ask at that point LOL.
    Anyways LOL, after that.... the HO2S monitor will evaluate the upstream (S1) for using as fuel control... to be basic.
    and the down stream (S2) monitors for proper converter function....if you have say... an injector crappin out on cylinder 1 or whatever you'll get an o2 code for that bank or lets say it's a code: PO133... (an HO2S sensor circuit slow response code description and one of many O2 codes) that don't mean replace your 02 sensor exactly, it could be an exhaust leak, a shorted or open wire in the O2's circuit somewhere,, Improper fueling, inlet air leaks even a MAF sensor but yes it could be a detriorating O2 sensor... but WHY? You have to figure that part out. see what I mean?
    An O2 code does NOT always mean a bad O2 and if it is bad WHY did it go "bad"? was it contaminated by bad fuel? coolant seeping into the cylinders? (which is VERY common with the 4.2) to be sure, you have to check this line of stuff out- run a "flow chart"... otherwise your guessing,, and 9 times outta 10 you'll lose... ie, your new sensors will crap out later from contamination caused by something else thats wrong, and you'll get the code again later or in other cases... say in this example you had an inlet airleak and you replace the sensor and the code imediately pops right back up LOL.
    That's why the autozone "kids" get under my skin by selling parts based on a basic trouble code scan.
    It's like a pharmisist diagnosing a complex medical condition and then selling you some pills for it... haha.
    I don't want to put you through college here lol, but I'm trying to give ya a basic understanding and I'm not a good teacher at all... couple that with a headache and being tired from fishing last night until 4 am, I might ramble too much if I'm not careful... If you can tell me the code, I can help you to figure out for sure wether it's simply just the sensor or something else... my guess at this point is it's more then likely something else-- and that "something else" needs to be pinpointed and repaired so's you don't spend time and $$ on O2 sensors only to crap them out again.
    The code will be like "PO and 4 numbers after that like say PO136 for example or whatever ~Bill
    I think I'll go back to bed now....
     
  6. drpepper

    drpepper New Member

    Messages:
    6,133
    State:
    Indiana
    Here is also a good Idea... unless your a diehard do-it-yourselfer:wink:
     
  7. drpepper

    drpepper New Member

    Messages:
    6,133
    State:
    Indiana
    I meant PO and 3 numbers after that LOL:roll_eyes:
     
  8. bootshowl

    bootshowl New Member

    Messages:
    2,288
    State:
    Indiana, J
    Thanks Bill, for the info. Guess I'm gonna have ta quit trying to work on my stuff...to much for me. But it made sense that the failed plug would foul the sensor. And the second code said the sensor on the other bank had a slow responce. And the info I could pull up on searching bout the sensors....most of it said replace em before they fail. (?)!!!
    But on the bright side, both have a year guarantee, LOL. I put the bank 2 sensor on yesterday, had the code cleared, and will wait for the light to come back on. Right after I replaced the bank 2 sensor, I could notice the engine smoothed out....it was running just a lil rough at idle. I could feel and hear the difference. It's purring, wish me luck. When the light comes back on I'll try and find someone like you who knows what their about.
    I agree with ya on the parts guys. And ya never get the same guy twice.
    I'm just on a fixed income, and try an save $ any way I can. Sure appreciate the feedback.
     
  9. drpepper

    drpepper New Member

    Messages:
    6,133
    State:
    Indiana
    Well good luck friend, look me up if you need me... if so maybe we can hook-up, I'll come down and diag your truck -you show me where the fish are on the Ohio:wink::big_smile: